Indeed, as @jspaleta has made clear, gaming is not the only use case here; it’s just the most visible. OBS, legacy games, legacy enterprise software, etc. are all software that would become problematic. More than that, it’s not just legacy software; some groups (ie valve, obs) are still using 32 bit in actively maintained software.
Some stuff is only just now finally adopting 64 bit, too. WASM (web assembly) only provided a 32 bit address space until January of this year. The rust WASM64 target is still experimental, with WASM32 being the default web target for rustc. GCC’s people have indicated there’s problems on their end too in the mailing list.
The way I see it, the main usecases in terms of end-user visibility are gaming and some legacy software. However, there’s also concerns from developers of said software, and there are still 32 bit actively maintained libraries in the wild for one reason or another.
The entire x86-64 bit architecture is itself technically a hack, and the fact the entire desktop world operates on it has led to this problem. But it is what it is. As long as 64 bit processors can still run 32 bit software, 32 bit stuff will still be expected to work by many, both users and developers. The only reason Valve even released a 64 bit Steam client for Apple was because of Apple Silicon and the EOL of Rosetta.