If anyone is genuinely interested to share their excitements then I don't think they should not utilize this opportunity. With the individual threads everything buries after couple of days. A self praised topic shared two years ago is gone back in so many pages that it's almost not visible. But with this topic when someone needs inspiration they know that they are getting everything in one place and they can easily spend time on reading one after another.
Previously I had the idea of creating a special thread that could be used by anyone who wanted to celebrate rankings:
Celebrate your rank up here [Junior Member - Legendary] but it didn't seem to get much support so I had to bury that intention and lock the thread.
I just think that celebratory thread are good and so far such thread are allowed because they don't break the rules
[if not too much] with free speech considerations in mind. I also have a celebratory thread, although it's currently locked and will moderate it periodically when I reach certain milestones to keep myself motivated and reminisce about my forum journey.