Chieri no Koi wa 8 Meter - Vol. 2 Ch. 22.1

[Derklord]

Unless im remembering wrong, this isnt because mouth to mouth isnt useful, its more because the average person isnt properly trained to do it correctly.

Not quite. It's much more important to keep the blood circulating, because there's quite a lot of oxygen still in the blood. The recommendation is two 'breaths' after a set of 30 chest compressions, as it's very important to keep the latter going uninterrupted.
If people feel too uncertain on how to properly do mouth-to-mouth, or there's serious hygenical reasons (the unconscious person is likely to be sick), doing only chest compressions is actually recommended.