Of course there are scenarios where $10K MRR is possible quickly, but there's no way that is what most successful software businesses look like in 3 months.
It's really a way to frame the product launch by forcing you to ask hard questions about what you're doing. If you don't even see a way for the product to reach $10k/month with a short-term plan, maybe it's a side project rather than a startup? Or maybe the product niche is too vague or unprofitable, and you need to work on that first?
I'm still a crap entrepreneur, but I've become slightly better at teaming up with people who can make it happen.
If it's a side project, that's a different game. A side project doesn't need traction to be successful for its creator.
I don't know how much Atlassian made in its first three months, but they are one of the only bootstrapped tech companies to go public in the last 2 decades. It took them 15 years. While this is not necessarily the fastest path to success, I 100% believe it deserves immense respect. They're one of the biggest success stories in tech as far as I'm concerned.
(Of note, Atlassian has mainly focused on enterprise markets)
I think that for most people, if they abandon anything that's not already a huge success three months in, they'll just end up bouncing from one thing to the next and never seeing anything through. It's virtually impossible to bootstrap that quickly, and I'd be surprised if many of the big VC-backed startups we've heard of hit that either (certainly not Google or Facebook who weren't even monetizing yet at that point).