My hill is that on the fediverse, if you think something is worth showing to others, you should boost it.
Even if it looks mainstream. "It's a comic strip, it's a meme, I bet people has already seen it". That only works for the large places like mastodon.social, but not if you're being followed from smaller instances.
On the edge of the network, receiving popular posts is harder. I like to boost things in case it helps someone out there discover cool things and accounts.