So much of that "took years" is because they didn't know exactly what the "years from now" state they were building in advance. Another huge chunk is because they started getting customers and had to respond to customer needs, demands, scale, bugfixes, preserve uptime, etc.

And even then, "enterprise" was often a dirty word in these circles. The over-engineered would-be-swiss-army-knife vendor that was mediocre-for-everyone but excellent for nobody.

I have built many tools in the recent past for myself. None of them need to be "enterprise scale." Most of them would be worse for it because the agent output suffers when the pile gets deeper and it's just adding more piles on top.