PNG vs JPG in /a/

As anyone using /a/ has noticed, people still keep posting PNGs in cases JPGs would be much better. And now some are just doing it for trolling purposes... I don't care about my connection, because I have no download limit cap and have a decent one, but what about 4chan's bandwidth (which is already 100% in use CONSTANTLY) and people on slower connections?

So what do you guys think... warning bans to people for posting PNG screencaps or remove PNG support from /a/ altogether? Because PNG is mostly useful for wallpapers -> /w/ or high resolution stuff -> /hr/.

>>2
>>3
Trolls. You don't get it, do you? This is not about users, it's about 4chan.