Why ban champions to begin with?

I've been banning none since and before the new draft system was put in place I'd ban champions with the lowest play rate when I was team captain (basically the same as none). Me and my Duo partners constantly get in to debates about whether or not this is a good route to go. They'd usually say something along the lines of, "ban x champ because hes op".

Heres some of the benefits of banning no champions IMO:

• leaving a strong champ open sometimes makes the FOTM (Flavor of the month) players pick that champion and proceed to do horribly (feed meh pl0x).

• even in the case if somebody is well versed with said champ leaving them open allows me to get more experience playing against that specific champ so even if I do sub par against said champ the next time I go against them I'll do much better in said match up.

• thinking back to when I used to ban champs I used to just ban whatever I got stomped by. this in turn would (i know this sounds cheesy) give a psychological hold on my psyche and every time I'd even see the champ would make me become instantly tilted. After doing no bans and learning how to deal with counters its not a problem anymore. Think about GD and Yasuo.

• FOTM Champs are picked constantly. allowing a champ to go through allows you to come up with a counter match up (if you practice the counter champ)

What do y'all think?