Medium has done well in this respect, but never forget that it is someone else's platform and could literally VANISH overnight, if its owners pull the plug. I've seen this happen too many times to put all my eggs in one basket. ALWAYS make regular backups of your content, and always have your own platform (if you can afford it) for SEO, if you want to be findable.

Hey, Patrick, here, knows how "findable" I am, online. LOL