jared If you are setting them up as a VPS as opposed to Shared Hosting, fair call. But that VPS will have its own dedicated IP and the functionality exists today.
Even then the $10/mo would be far better invested into a third-party smtp service (SMTP2GO/Brevo) or in the case of shared hosting, Mail Channels IMO. Unfortunately as you have pointed many mail providers (O365 the main one) simply range block entire ASNs from all the major VPS providers.
IP reputation in the past used to big thing, however many reasons of why it used to be done are simply not true anymore (dedicated IP's for SSL pre SNI).
You are a far braver man than me letting users send out of port 25 on their VPS and providing them email-deliverability support!