> Double so if that company sends marketing emails disguised behind support@company.com

That’s typically not a disguise but a clear means of indicating that you can reply to the email

No, sending marketing from support emails is almost certainly trying to game spam filters. Marketing@company.com would work for the allow replies purpose.

> sending marketing from support emails is almost certainly trying to game spam filters

That is not how spam filters work.

If I've interacted with a specific email address, like support@company.com, my email provider will put them in my inbox.

How is it not a disguise? It means you can't block marketing emails without also blocking the legitimate support emails.