Spending engineering time to save sales time is only viable at very sales-oriented but lower ACV products and even in that case, onboarding is generally focused on very core product functionality. Because sales deals have to be >$10,000 ACV to be worth it for the business, sales generally spends it time on C-suite focused features (SSO integration, security controls, auditing).
Not to negate your point: having a good onboarding helps sales, in the same way it helps customer support. But in practice, I wouldn't use that argument to measure whether or not the onboarding flow was doing it job. Nor should the sales team be able to blame the onboarding flow for low quality leads. Money invested in a good onboarding flow should pay off in onboarding/engagement.
Not to negate your point: having a good onboarding helps sales, in the same way it helps customer support. But in practice, I wouldn't use that argument to measure whether or not the onboarding flow was doing it job. Nor should the sales team be able to blame the onboarding flow for low quality leads. Money invested in a good onboarding flow should pay off in onboarding/engagement.