Agree mostly, however if you are a early-mid stage startup gaining traction and have enough of an engineering understanding to not become too coupled, then you

Agree mostly, however if you are a early-mid stage startup gaining traction and have enough of an engineering understanding to not become too coupled, then you can basically play the vendors against each other and get startup discounts or other types of discounts by swapping. I've heard of cases where vendor A gives a big discount to the tune of a the most recent year of annual billing from vendor B if you can prove that you most recent bill from vendor B is 0 due to completing the migration.