In reality, only some Pentium 1 compatible motherboards can support enough ram for you to actually run Linux on a Pentium 1. Even if you don't run into ram problems, you'll run into bios related problems. I would suggest anyone trying this in 2024 to not even attempt it unless you can get a socket 7, and preferably a later socket 7 motherboard at that. The closest thing I can come up with to a reason not to drop support for 486 (the cpu before the Pentium 1) is that a 486 is a lot more possible to put on a custom pcb than a Pentium 1. Some of the more basic arm cpus aren't even as powerful as an upper tier 486 (but better arm cpus aren't that hard for hobbyists to get). Anyone die-hard enough to want to try to run Linux on a fully custom made computer like that would have better results using an arm or risc-V chip instead.

I am curious why they're dropping support for 486 but not Pentium 1, pentium 2 and anything not capable of SSE1 or later. mmx isn't even that good but I guess gcc does technically support it.

I wonder if they're going to drop 486 support in gcc as well. It can still compile for 386. You have to seriously strip down the kernel to run Linux on anything that old. Maybe 486 users (all 2 of them) should switch to Temple OS.

You may find this interesting:

Ubuntu is nearly 20 years old so we wanted to see how the first versions compare with the upcoming LTS. Unfortunately installing Warty turned out to much harder than we thought it would be.