It struck me that, maybe, it used to be easier to build software. But it seems the reverse should be true. I say it should be easier for me to build a DOOM source port now, on my M1 mac, that it was to build many years ago. But it seems like it's not. And if it's harder to build, then it's harder to write. The original DOOM source is tight, but chocolate doom (no disparagement) was a multi-megabyte repo pull.
Is this a general thing, or am I overfitting my 1 experience trying to build ancient software on my modern hardware? :)
I think the opposite tends to be true. You're dealing with "a multi-megabyte repo pull", because of SDL2 and other dependencies needed to build Chocolate Doom.
Writing on top of SDL2 etc is obviously easier than having to implement everything from scratch. It makes building more cumbersome and will usually yield a more bloated and less efficient end result than having John Carmack hand-optimizing everything, but it lets you get the thing working well enough - on modern hardware.
Back in the day of original Doom, when every clock cycle and every byte counted, and ready-to-use libraries were few or non-existent, writing was much harder.