Companies will company, if there's an open door to spam things they will. SPAM in the email realm I recall seeing a stat that it accounts for somewhere around 90%+ of email traffic, so thus all the crazy hurdles of ip lists, dkim, spf, etc.
I've seen accounts created on Mastodon for just that purpose. They get a warning that such is not the platform's purpose, if ignored into the ban bucket they go. The problem is it's easy to create accounts unless the admins want to manually review and approve every applicant. External IP blocks work to an extent, but are always going to be reactive in nature getting banned after they've been reported. Ce'st la'vie (or however it's spelled)
If there's a plus side to it, their presence here means that someone thinks the network reach is enough to be worth the effort to post something here to get some kind of return.