Hashtags do not replace groups.
No one moderates them. They’re easy to hijack and spam. And there’s simply no permanence to them.
Which is why, if you actually want to discuss something, it’s better to tag a group. For example, if you want to be part of an actual PC gaming community on the Fediverse, it’s better to tag @pcgaming@lemmy.ca than #pcgaming.
This needs to be common knowledge because people new to the Fediverse do not know about groups. Hell, I’d say people who have had Mastodon accounts for years still don’t know. And that’s a shame.
I follow topics and have discussions on Lemmy, keep up with individuals and announcements on Mastodon, and look at cool photos on Pixelfed.
None of my accounts are following anything on other systems.
The reason I’m in this community is for discussions like this. We disagree on the nature of using he fundamental architecture of the Fediverse.
I think using Mastodon to engage in Lemmy discussions is extremely awkward without the threading to keep it all organized. Equally, Lemmy is designed specifically around following communities. Following individuals on Mastodon breaks the pattern of the feed. And good luck following either Mastodon accounts or Lemmy groups in Pixelfed.
However, having multiple decentralized servers within each system, is plenty of reason for the Fediverse to be better than a centralized platform. They don’t Need to interoperate with each other.