Here is a poll about expected behaviours on Mastodon:
Should original toots that begin with a @ (mention) be treated similar to an original toot (regardless of @) (current behaviour) or similar to a reply to another toot (e.g. not shown to your followers who do not also follow the person you're @'ing) (Twitter behaviour)
@gargron so if I follow you, but not the recipient, and I reply, you find that annoying?