Imagine being software developer with a sense of professionalism and dealing with your customers as they are, even if it's annoying a tad bit of extra work, instead of telling them to sod off if they're using a browser you don't like.
Even MS has had modern.ie[0] for years. Until then, Safari users are on their own[1].
[0]: https://developer.microsoft.com/en-us/microsoft-edge/tools/v...
[1]: https://drewdevault.com/2017/10/26/Fuck-you-nvidia.html
You can apply for a free BrowserStack accounts for open source projects btw[1]; it's still a bit of a pain, but better than nothing.
Now imagine a platform where users are allowed to use a better browser which supports more image formats and saves their battery and bandwidth instead of being locked into a single closed piece of software for ever and ever.
And imagine a world where owners of that platform would understand something as historical as importance of free market competition and huge damage of DRM locked plaforms.
Do non-web software developers support every CPU architecture? Because I'm sure I've heard of apps that not run on macs, or just windows and not Raspberry Pis.
Supporting jpeg however is very low cost, with very high benefit: about 20% of browsers don't support webp. It's a small nuisance, not a substantial amount of continued investment of work like supporting a new architecture.