Correct. The last line of my comment is most relevant to this chain.

More specifically I could say that while many optimizations might be general-use or discoverable, others may be specific to said old system (or maybe getting around limitations). That and this level of optimization would be diminishing returns for even the lowest of modern systems (but obviously nearly required for the target hardware).

Making a minimalist and well-optimized game for desktop PC is going to be significantly easier and with more of an audience than trying to target most other hardware. There are also fantasy consoles like TIC-80 or WASM-4 for more modern/open targets that likely have better documentation/communities (or the community for whatever language you are using instead).