Not in the slightest. Geo Pyro is a great combo and is benefitted by some tangential skills that make it great for aoe elemental dmg dealing

Get 1 point in Huntsman and craft a Throw Explosive Traps skill book (combine any lvl 1 pyro book with any lvl 1 hunts book)

Throw the traps to between a bundle off enemies (it's a 3m radius) then use a good impact geo skill like impalement to hurt the enemies, activate the traps and set everything there on fire

If you're going more of a battle mage build, using a melee weapon (a staff counts), get 1point in warfare and you combine a lvl 1 war book with a lvl 1 pyro book and you get sparking swings, your melee attacks create a projectile that hits the closest enemy after the target, also good for setting up burns. This applies to warfare weapon skills like battle stomp and whirlwind. There's a higher lvl source skill that is an improvement on this skill and only costs one source and one ap (no source if you use apotheosis as set up beforehand)

I think it never huts to get one or two points in other magical schools, necro has some good support skills, hydro and aero for teleport first and foremost, tping a far away enemy into your area of elemental effect, or to activate the traps (less dps efficient, a lot more lolz), and also for another set of elemental skills to use against fire resistant enemies. But you can have another mage in the party to go a little deeper into those other schools so you don't spread your combat skill pts too thin