Yeah you could, and that's why it's pretty solid branding. Just like "Instagram", it can be said pretty easily in most languages and it abbreviates nicely (Insta/Masto), so you can make it short.

It's arguably better to have a shorter one or two sillable word as a name, but that is a close second choice.

Now, the toot thing is dumb, and since it's only vaugely official I insist on calling them "posts" on all apps.

You want to talk about a dumb name, let's talk "Fediverse", which may be the stupidest word conceived by any human since "blogosphere", sounds extremely goofy and is just inaccurate and redundant. I mean, "The Federation" was right there, sounds badass and it actually already means "a collection of federated things". A "fediverse" means nothing, but if it id, it'd be "a collection of federations", not "a collection of federated things".

Three syllables is too many? Your username has the same number of syllables. Many actual personal names have the same number of syllables. Three is the magic number.

Mastodon is WAY cooler than your username, which looks like a misspelling of "tomato tool".

Masto sounds like slang for breast removal surgery.

The number of syllables does play a role on word length, but keep in mind that most languages have faster syllables than English, due to lighter phonotactics and lower tendency towards monosyllables. (It's like English tries to cram too much info per syllable, and as a consequence each syllable gets a bit loooonger.) As such something like "Mastodon" might sound verbose in English, but in [for example] Spanish or Japanese it's relatively short.

I also like the reference. It's a critter, big, and generally associated with elephants, that are seen as sociable and smart.

(Since people are talking about your username: it reminds me some alcohol extracted from tomatoes. Ethanol, propanol → tomatol. I do agree with you that usernames aren't good names for social networks, mine for example wouldn't roll at all.)