1 - hostile to newcomers? Not my experience - but it is true #mastodon would benefit from a “new users” place. Perhaps a #NewUser hashtag
2 - poor discoverability: follow some hashtags that provide reliably diverse content of follow a super-booster like @lisamelton
3 - too serious? Follow some hashtags like #bloomScrolling #mosstodon etc.

hmmm… looks like all 3 of these valid items could be handled by recommending some hashtags during on-boarding.