Well that's a lot to unpack. Saying AMP connectors doesn't really mean much of anything because, for starters, AMP (TE Connectivity) owns Deutsch.
In the retail space, at least, DTM's largely been superseded by the lower-cost ATM line. Weatherpack and Metripack are pretty common in the US because GM developed them and GM is a huge company. The only company that comes to mind for using DTM connectors is Caterpillar, so you'll definitely see medium duty trucks with DTM assemblies.
The two automotive companies I'm most familiar with (80s Volvos and 00s BMWs) use keyed connectors all over the place. The Volvos used off-the-shelf washing machine connectors (AMP /(junior )+(power )+timer/) that can be had with keyed connectors. BMW saved pennies by going with high density connectors and small gauge wire. Most of that stuff is off-the-shelf as well, but often with proprietary keying.
Both DTM and Weather/MetriPack are pretty bulky compared to what's available now though, and when you're talking about 100 or 200 pin connectors size probably matters more than a few pennies. And, of course, once you start adding the retention doodads to MetriPack assemblies you start getting closer in price to DTM style stuff. The simplicity of the wedgelock design means fewer parts to stock and potentially faster assembly which could easily negate the more expensive housings.
This will never take hold. These are extremely expensive vs weatherpack and other cheap connectors. Auto manufacturers care about literal pennies.