hashtags have better use in platforms like mastadon

Says who? Because that's how the old platforms used it? I think we should really be moving past the direct influence of these corporate platforms and on the fediverse that probably means something of a well understood common language (like @user@instance or !group@instance). Hashtags were only ever a thing on twitter because the users just started using them and full text search was sufficient to handle it (this is more or less the position we're in on lemmy). Direct support didn't come till much later.