Pardon my ignorance, but isn’t Tumblr just another microblogging site? Wouldn’t mastodon be a viable alternative?

Not that in complaining that there’s another fediverse software, just trying to understand what is the difference or if it’s just splitting hairs.

It's all just little text packets, this place included.

But hey, that's all social media. The slight differences in threading, text limits, media embeds and share mechanics do matter.

They do, absolutely. But what are those differences between Twitter and Tumblr? I thought it was just a different CSS.