For things that you're using by yourself, sure, it's doable. However, for content creation, it's pretty hard. Some of those alternatives just don't have the critical mass yet. Maybe it would be an option to do both in parallel for some time before switching completely, but might not work for everybody.

Practical example: I'm a hobbyist photographer. Small timer, less than 1000 followers. My livelihood doesn't depend on this, but I'm still serious about it. I mainly do concerts and sport events (so a lot of things involving other people) and my main outlets are Facebook and Instagram. Switching to something else would mean either 1) that no one will see my work or 2) that people will see my photos on the alternative place, they'll copy them over and they'll still end up on Facebook and Instagram, but this time without my creative control (thus badly cropped and recompressed several times - so even if I pay special attention to those things when publishing by myself, the effort goes down the drain when someone else does it).