It depends on what you mean by 'popular'.

Do you mean popular in the media, in people's general conception of 'badass weapons?'

Or do you mean... actually popular, in real life, everyday ownership and usage?

The 4 chan post says 'only popular because of how they're depicted in media'.

If you are using the first definition, this is a meaningless tautology, thing is popular in media because thing is popular in media.

If you are using the second definition, this is just a false statement, hardly anyone actually owns or uses katanas compared to revolvers.

Both absolutely have been emphasized as 'cool guy weapon' in media.

But probably 1,000x to 10,000x more people actually have revolvers than katanas.

Both revolvers and katanas are largely popular in media and general public conception, becauase the characters depicted using them are often well written compelling characters, or at least are the heroes of compelling plots, and their usage of them is often depicted as extremely skillful...

..., but revolvers are far more popular in real life, because they are far easier to use, and more practical.

If you can be more specific with your question, I can probably be more specific with my answer.