This is just personal opinion, but most luxury cars today are not what they used to be. As corporate took over, it brought a lot of cost cutting and standardization with it. Different divisions engineering their own engines, and sometimes even platforms, became a thing of the past, and a lot of luxury cars became "dressed up" versions of their more affordable counterparts. If we specifically look at the full size SUV market, whether you're looking at a Ford Expedition and a Lincoln Navigator, or a GMC Yukon and a Cadillac Escalade, or a Toyota Land Cruiser and a Lexus LX570, the concept is the same.
Some brands, such as Lexus, claim their parts and components are held to a much higher standard than their more modestly priced Toyota counterparts, and of course NVH and other elements are further refined to accommodate the higher price point. But drivetrains are often the same, as are many other core elements, which, ironically, is also a selling point - "Yeah, you can use Land Cruiser brake pads from the Toyota dealer on that LX570!" Some components, such as suspensions may be further tweaked and refined, along with different appearance packages, but that seems to be the limit.
I'm not going to pretend I know much about other brands, like Land Rover, or higher end luxury cars like a Rolls-Royce or Bentley, but generally speaking, those are in their own class and a Bentley Bentayga is not a direct competitor to a Lincoln Navigator.
Even within the same "class" they're all crammed into as "full size SUVs", I personally don't see a Lexus LX570 competing with a Cadillac Escalade, but more so with the likes of an Infiniti QX80. One is based on the Toyota Land Cruiser, the other on the Nissan Patrol, both of which off-road beasts with a big emphasis on off-road capability. The Tahoe/Suburban based Escalade is a super sweet truck, especially the new 2021, but even with four wheel drive, they're designed more as on-road vehicles than off-road.
This becomes clear when you look a bit further; you want an armored SUV, sure, you got the Land Cruiser and a Suburban, both armored to B6 level. While the Land Cruiser, be it gas or diesel, can barely get out its own way, the Suburban still takes off without a care in the world about the extra weight, and are truly sought after to the point where people fight over them. Hitting the gas on the Land Cruiser feels like stepping on a wet noodle compared to the Suburban.
By the same token, the Yukon Denali has a made a solid name for itself in the Middle East for being the close protection vehicle of choice; it takes any and all abuse thrown its way; the 6.2L doesn't care about the 4 adult occupants, each weighting 260 lbs, or their gear and weapons in the trunk, or the 300 lb push bar up front. It out accelerates its competition, handles extremely well with its adaptive suspension and law enforcement usage has been a huge selling point for civilian buyers. They tested a 5.7L Land Cruiser for exactly the same purpose, and it fell flat on its face. Despite the higher axle ratio, it didn't accelerate nearly as well, the suspension wasn't well suited to evasive maneuvers and they had issues with brake fade once it got up to high speeds, which also posed other problems running at 4,500 rpm in 120°F. Now take the same Yukon Denali, or Suburban, and the same Land Cruiser off road, and it's a different story altogether. The Land Cruiser will easily outdo it's GM counterparts, which at this point fall flat on their faces because that's not what their stock suspensions are built to do. But to Average Joe, they're all "big" and "four wheel drive", so they're all in the same class.
Thanks to marketing that has lead people to believe SUVs are "invincible", which has been their primary selling point, gone are the days of a transfer case marked 2H, 4H, 4L, etc. and now it's a dumbed down version of regular driving, snow, rain, blizzard and every other possible climate condition out there which electronically tweak different settings. This then lead to the CUV as your ultimate "adventure car" with great gas mileage and barely any proper off road capability. Average Joe, without any knowledge of how the system actually works or its limits, thanks to "the sky is the limit" advertising, thinks he can easily outrun any other car on the road in the snow, and gone are the skills of driving in snow with your average two wheel drive vehicle. Over confidence, and poor knowledge of basic maintenance, then leads to other disasters.
Which takes me back to my point about corporate takeover; John and Jane Doe don't care if the Navigator they just bought is really an Expedition under the skin. It's big, it's got four wheel drive, it's "invincible", so it fits the bill. They'll still lease it to impress the neighbors, neglect to do any proper maintenance other than oil changes at JL, and when the pads are finally grinding into the rotors, they'll turn it in and lease something else with the McDonald's fries still stuck between the rear seats.
The same marketing applies to luxury cars; back when it meant something to have an 500 cubic inch Cadillac V8 under the hood, that was the selling point. Now marketing and selling points are autonomous driving capability, seats made of planks of wood in the name of "sporty feel", smartphone connectivity and illuminated air vents.
At this point, does it really matter what platform or distinctive engine a luxury car is equipped with? For a Rolls-Royce buyer, maybe. But for a Lincoln, Cadillac, Lexus, Infiniti or Acura buyer, highly unlikely - especially when a lot of the same features are offered on lower end counterparts of the same platform. You're ultimately paying for the "prestige" of a brand name, which unfortunately, a lot of these luxury brands now cater to.