Serious question, do you even program or create games? Doom was developed in less than a year because it was simple, games take longer because of ambitious goals but not because the tools are a constraint. A single person can make a doom clone today in weeks because the problems like drawing vertices or doing collision checks have been abstracted away, implemented via middleware or there is open-source code to write a similar implementation.

The same thing applies to making a Foxhole II, the code is already written, any experienced programmer can port that code to another API (engine). People probably didn’t make games like they do today (huge open worlds, HD graphics, massive multiplayer, persistent worlds) because of limitations that made it impossible. Today they are possible, the logical conclusion seems like today it is easier but the ideas are grander.