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.
Maybe this is where they are heading? The heavy sales team route requires larger customers for it to be worth their time converting them to paid users.
They might be looking to cut back on sales and try a more automated approach to convert people to smaller plans.
They might be looking to cut back on sales and try a more automated approach to convert people to smaller plans.