I went the whole hog and set up IG, FB and Twitter pages. Honestly I really can't be bothered to keep the things updated. As my motovlog accounts are all separate from my personal accounts, it's a lot more effort to keep going than one's personal stuff (which I don't do either). I have not noticed any advantage to having social media platforms, unless you are very active.
Interestingly I've noticed that some people who asked me via PM on one of the social media platforms to sub to them, have a lot of subs but a slightly disproportionate amount of views less than they should have. So a channel with just under 2000 subs only gets about 120-150 views per vid. I suppose that supports the suspicion that people on one platform may not go over to YT. I've noticed on IG that most of my followers and "likers" over there never comment on my vids, so I can only assume they don't watch them either.
At this point my social media platforms, especially FB and Twitter, are just a token effort. I still interact with other motovloggers on IG but that's about it. I think being active on YT is probably as, if not more, beneficial to your channel