This is fascinating. I am a small speaker manufacturer and drivers to me are one of the thing that stressed me less. There is a lot of work that goes into choosing the right driver in terms of testing with your cabinets and materials but there are lots of bigger manufacturers that use stock drivers that make AMAZING speakers.
To name a few, Wilson (small mods in some cases) Avalon, Marten, Joseph Audio all use stock drivers. These guys make some of the best products in the world and they use stock drivers from Scanspeak, Eton and Accuton, Accuton and SEAS from the companies above.
I have been told that Revel has since moved production internally but the drivers in The Performa3 line were SB Acoustic when it launched. Doubt this? I still have a pair from years ago with SB drivers in them. The tweeter had a waveguide designed by Revel. That was what made it their own.
There are crappy speakers out there and you can spot them and avoid them. Check out this series of articles from audioholics:https://www.audioholics.com/loudspeaker-design/high-fidelity-loudspeakers
See links at the bottom of the page for other relevant topics like this one on the explicit elements of a driver:https://www.audioholics.com/loudspeaker-design/loudspeaker-drivers
in the series they touch on all aspects of speaker design other than utilization of exotic cabinet materials (aluminum, fiberglass, carbon fiber, stone, etc...) but those materials are clearly superior to MDF based on guiding principles outlined in this series.
I will admit that i designed my products so that if Audioholics took them apart, they would be pleased with what they found.
Good luck to you in your shopping.