I mean, the fix is not to write systems where you can specialize in the combat bits of the game to the exclusion of all else. Every character should have access to a good set of (distinct) utility options, and being competent at out of combat things in at least some fashion should be considered the normal expectation. If a player wants to challenge themselves by refusing all the utility options, that's fine, but IMO it's like going to a D&D game and saying 'I'm going to play a pacifist who refuses to participate in combat in any way' - get explicit buy-in from the group.
Those options don't have to be spells, but they should be sufficiently well-defined that players can plan around them - it should be possible to at least somewhat know what you will and won't be able to do when it comes down to it, the way a Fighter would be able to say with some confidence 'I think I can take a half-dozen goblins' and can conceptualize the specific ways in which that might go wrong 'oh, but not if we're fighting in the dark' or 'oh, but if they have cleric support it could be dicey' or whatever.
Some things are close to this in 5e, others are much further away. Spells are very definite, you can definitely know if you'll be able to fly over a 100ft gap or not. Stuff like lockpicking is probably close enough to count - you might not know the DC in advance, but its pretty unlikely for the DC to be impossible, and given time you can be pretty sure you can get it. Something like scouting planar portals to Fire or digging up blackmail material on a noble to get an invitation to the royal court? There are lots of factors outside of your control or estimation - it wouldn't be reasonable to make a plan around those sorts of things without prior confirmation from the DM.