"Not supported" on its own does not mean "actively blocked/disabled", which is what this is.
"Supported" means that they provide a certain effort for make the configuration operational for their users, by designing said support if needed and providing assistance as required.
Yeah they are just being lazy and not testing it... so rather than verify it works and fix bugs, they just check your browser agent and redirect you if you aren't using Chrome or Safari. So ghetto! Reeks of the late-90s/early-2000s "Use IE6" messages that companies used to put out when they built a site using Microsoft web components or proprietary APIs.
"Hey look, I can save my PowerPoint as a web page! And it even has the animations!" Except it's 2024, and we have standards, and for them to say, "Oh we don't adhere to the standards" is shockingly bad.
It may or may not work, but since that is a bad user experience, they disable it.