I don't think most people expected that to happen so quickly or frankly at all.
It might not all be open-source, and they are doing it with an expectation of long-term profit, but they are earnestly pushing the horizons (pun intended) of the field and taking-on lots of risk for everyone else.
It's undeniable now that they are a serious and innovative engineering organization, while Google is rapidly loosing that reputation.
Most new products fail at meta, because they become a "priority", throw thousands of engineers at the problem and get bogged down in managing a massive oversubscription of engineers to useful work ratio.
Threads happened because a few people managed to convince each other to take a risk and build a instagram/mastodon chimera. They managed to show enough progress to continue without getting fucked in the performance review, but not enough for an exec to get excited about building an empire around it.