Buckler great question!
From my basic understanding of CRMs, custom CRMs are a benefit to use because they allow you to build one that adapts to your business rather than the other way around.
This allows for your CRM to be more user-friendly and ultimately offer better data. If you have to force your business to adapt to a pre-built CRM, you might have to skip on important details and analytics to fit their mold. However, I've never used one personally so this is just from what I've read.
Do you use a CRM? Were you thinking of using one, if so for what reason? Super curious to hear.