"That is why I maintain there is more here than just "parts shortages"."
You're in all likelihood correct. Lionel is designing a completely new system, for one thing. MTH has downsized significantly and is redesigning their system. DCC is basically the same system, unchanged for decades.
The Base 3 was announced in Jan 2022 and planned for late 2022, so it's "only" four months late. The WTIU was announced in Jan 2020 and is about 1.5-2.0 years delayed. 1.5 years into that initial period, Mike Wolf considered closing MTH entirely. Stuff happens.
My guess is no more than 2-3 people are working on the Base 3 and 1-2 on the WTIU. I suspect NCE and Digitrax each have significantly more staff than that, given the size of the markets in HO and N, not even considering S, G and Z, which are much smaller but also tend to use DCC. NCE and Digitrax also do nothing but DCC, whereas Lionel is more like Marklin or LGB, with a full line of products.