As a DM/GM, I've never had a problem 'dealing with' min-maxers. Generally they are focused on combat capabilities, and as they don't also have Main Character syndrome, you just give them a meaty target to focus on and massage encounters to feel balanced. At least in the (many) groups I've played in, the min-maxers were rarely the trouble-children.
There are tons of DnD horror story channels and a subreddit if you are intetested in seeing the type of people that do ruin a campaign.
That said, there are some multi-class scenarios that call into question the RP. But as a DM, you just work with your players to sort it out or reflavor it (I'm looking at you Hexadin).
Again, using the rules to create a cool combo is a fun way for people to enjoy the game in a non-destructive way. It's just that there are times where other destructive behaviors get associated with minmaxing that things become an issue.
Main Character syndrome is often built on a framework of minmaxing and delusional self importance. But the delusional self importance is the issue.
On a great note, this is a CRPG, so in game at least, you are the Main Character and that self importance is implied.
Conclusion to my rambling: Enjoy being the MC and minmax if that makes you happy.
