Neil Young (Liontech) was one of the pioneers of command control for 3-rail. I think he came up with TMCC circa 1994 because at that time, there was no off-the-shelf DCC solution that would operate amp-hungry Pullmor motors in the electrically noisy AC track environment. It worked well enough that Lionel began "bundling" it with severaly new top-line locomotives. So although proprietary, it became a quasi-standard. Especially when Lionel began allowing competitors to offer TMCC in their trains as well.
DCC doesn't care how many rails are on the track, but I doubt that it would operate a Postwar motor very well. At a minimum, I think the motor would need to be isolated from chassis ground (outside rails.) If you have only new can-motored stuff, DCC should work great. The main roadblock to using it is the initial cost of the command base, handhelds, etc. Also, the effort of installing a decoder in each loco. If Lionel and MTH offered their locos "naked" (i.e., with no electronics in them) and for a lower price, DCC would be a very viable way to go, as long as you aren't interested in running your train at a club, or someone else's house.
For this reason and others, I like the "direct R/C" options better than DCC. With direct R/C, there is no command base. Just a receiver in the loco that modulates track power to the motor, and a hand held controller or phone app. This is exactly how Lionel's LionChief works. I also know of three aftermarket options: AirWire, RailPro, and Blunami. With a small "helper circuit" to condition the track power going into the decoder, you end up with a loco that will give you individual control on ANY layout. Hope this helps!
