We were one of these potential bigger customers willing to fork over thousands per month, but the unit cost was still too expensive for us. We tried to negotiate a better bulk rate, but their team was unresponsive and so we eventually went with another service that was more responsive to our needs. According to the article they only have ~3k paying customers, which means they only care about giant top tier customers willing to pay top dollar. Seems like a mistake to me, but what I only know from the potential client perspective.

Either you really aren't getting value, or you don't have many users of your own. $150/mo is much cheaper than building and maintaining something equivalent. $150/mo is nothing compared to even payroll taxes, let alone payroll itself.

I hope folks realize that's ok. Mixpanel made a conscious decision to start at $150 and understands that for certain people theirs no ROI at that price point. I mean Apple could sell a $300 iPhone but they'll leave that to Android.

For the reason you suggest (lock-in during growth), it seems to me that they are being foolish by not having a startup tier. Tens of thousands of $10/mo or $20/mo customers adds up to quite significant revenue.