The tracking system not functioning is not a server overload issue. If that was affecting GPS, my character’s location wouldn’t be working correct either. It's a software issue.

Millions of people playing affects the servers, not the coding of the game.

I disagree. Aside from not being able to login due to server overload, you also lose items when the app freezes. For people that pay for these items, you are losing money. The main purpose of the game is to hunt Pokémon, but with the tracking system not working, this cannot be done.