I haven't had a Facebook account for many years now, but I remember that what bothered me about their redesigns wasn't how they changed visuals to keep up to date. It was a rapid series of restructurings which meant you always felt you didn't know where to find things.
Craig's List looks dated, but remains incredibly functional and is still the top site in its segment. Its dated look doesn't scare people away. It is still very functional. That's the important part.
Yet Craigslist appears to be steadily losing traffic each and every year since 2017, so I’m not sure it’s the best example.
Meanwhile Facebook marketplace is nipping at their feet while they are staying static.
Clearly Craigslist is incredibly profitable and successful, and possibly more profitable in the short term because they aren’t investing, but IMO remaining static means you lose ground eventually.