CRM is more of a corporate buy-in for many companies.
It is very hard to have PLG in CRM. In SMB, it is probably easier, the sales team will look for CRM, but in many large companies CRM is a corporate buy.
But helpdesk, like a support team, sometimes is a corporate buy but in many cases teams will just use the helpdesk for ticketing.
They may even have something else for their customer support, but ticketing is a smaller, well-defined problem.
You have to understand and find that value for the teams.