Acne is a disease of the pore. It's not caused by dirty skin and it's not something you did wrong. Acne-prone pores shed dead skin cells much faster than normal pores do, and that buildup clogs the follicle and forms what's called a microcomedone.
That's the starting point of every single breakout, whether it turns into a blackhead, a whitehead, or something more inflamed. It can take up to 90 days for that clog to actually surface as a visible pimple, which is why results take time, and why a breakout you see today may have started forming months ago.
Managed, not cured
The important mindset shift here is that acne is something you manage, not something you cure. Just like you wouldn't expect to "cure" your need for sunscreen, you don't ever fully graduate from taking care of acne-prone skin.
You get it under control, you keep it under control, and if you stop the routine, the clogging process picks right back up.