As a maintainer of an RSS reader app which has its own inventory for suggested feeds, one of the uphill battles is sudden removal of RSS support from various sites. I have a list of feeds which are updated once a month and everytime some sites (both niche and big ones) drop RSS support (Reuters and YouTube removing option to export subscriptions as OPML are major blows in last few months).
The reason for these removals is also never given. If you look at those sites now, you'd feel RSS support never existed and nobody used them. So the reason for removal could be anyone's guess. Perhaps RSS icon didn't look good with other social media icons on home page, server serving the RSS feed shut down and no one bothered to check, forgot to add RSS option in new design/refactor or some PM didn't find RSS feed engaging enough and actively killed it.