You also get to a point in hiring where the field of sales/ops people judge you & your maturity based on whether you use a commercial tool like Salesforce/HubSpot vs build your own.

Can you imagine joining a tech org and they have a half baked phpadmin wysiwyg as a standin for github + code reviews?

While yes, you could calculate out how much the subscription is vs development time to build a simple CRM, the maintenance & mental overload is righteously terrible. Better to spend that effort integrating your foos to your bars than building a sales crm.