To be impactful.

For impact

Torqued

Memes come from the old internet days, when there were less pixels due to bandwidth. Impact is suited to readability with very few pixels. It's just become tradition, since most of the meme generators still use it. Just use GIMP, and you can use anything you want if it's installed on your PC.

What are we supposed to use instead? Papyrus?

Which are the good fonts for memes in our current time, with generally better net speeds?

Comic sans, as Jesus intended.

Also the white with black border on a bold font allow it to be read over any gradient/colors.

It's really up to the meme creator's presence these days, but readability is still important.

Which all fonts would be good for that?
Also, are memes in dark mode/background more common now?