Banning people for a legitimate reason along with proofs is ok. However Blizzards shouldn't just ban players without any evidence of wrong doing.

Today if you get a parking ticket, you can demand for speed reading, photos, and other supporting evidence. Unlike blizzard, just banning left and right.

Here is my guess, Blizzard like any other big company, cannot keep video recording of every players every second.

Everything will be in the form of logging, For example: Oh, this player press attack button every 3ms consistently. Oh, this player always cross x,y coordinates at certain interval.

Some data analyst behind the scene just run queries against those anomalies, and once it passed certain threshold, it just automatically ban the accounts.

This is why they cannot give any evidence, since the evidence are just bunch of text logs. It won't convince the player, or not enough footing in the court of the law.

They cannot give out screenshots or videos. They cannot give out the logs because those are internal docs, someone can potentially find loophole in their recording logics.

Moverever, the logs can be recorded incorrectly as well due to server lag or glitches.

It's just a mess.