The invite system is ostensibly rate limiter and moderation tool, rather than a hype machine. They've mentioned getting rid of it soon. Maybe they "missed the boat" in some sense, but I'd rather see steady and sustainable growth.
Dorsey hasn't been doing them any favours for a long time, he's all but publicly disavowed it, deleting his account to focus on nostr. He's still on the board of directors last I heard, but if his public statements are anything to go by, he's not actively involved.
With a social network, steady and sustainable is usually not an option. If they don't have a strong launch when they remove the restrictions they'll fade into irrelevance within a few weeks. Threads had a surprisingly strong launch and it still has an uphill battle to climb if it wants to challenge Twitter and that's in spite of all the ways Twitter is attempting to self-sabotage.
Explosive growth is not a requirement. Take a look at reddit's long-term trajectory, for example. It's remarkably linear (although I have a feeling it's not going to continue for much longer)
Dorsey hasn't been doing them any favours for a long time, he's all but publicly disavowed it, deleting his account to focus on nostr. He's still on the board of directors last I heard, but if his public statements are anything to go by, he's not actively involved.