See, I don't fully agree with this. I do understand that there is typically a good amount of focusing in a build, but when you hit level 5 you're always getting 4 ability boosts. Having a +1 in a Stat is generally not great for a primary stat, but as a backup skill stat it can still be useful. If you keep that skill up along with the ability, it'll track close to 50/50 with leveled DCs.
The bigger problem here in that regard is not stats, but something
@Staffan has mentioned previously, that most classes don't have quite enough skills to keep everything at their maximum. Now my argument would be that all skill checks shouldn't always be leveled with the characters, but I'm also not writing APs here.