One interesting thing is that money invested into a good onboarding flow is money saved by saving salespeople's time. Companies with minimal onboarding flows need a very active sales force to actually close b2b customers. You need some sales regardless, especially for closing big companies, but you need less with solid onboarding.
Source: I've worked with the marketing teams of 15+ b2b SaaS companies (https://twitter.com/kevinwlordbarry/status/12222616726367109...)