It's the combination of the most possible number (21) of the ultimate term top + the fact that this results in the most possible number of characters (63) + the fact that it ends with the ultimate TLD .top
top has 3 L, it can't replaced by other superlatives, top means top, best means best, a means a and z means z.
But top means top.
That's why it's used worldwide as the ultimate superlative in economy, media, news, radio, TV, web etc.
And that's why it is nowww used as a TLD hahaahaaa it's time to realize it.
Also, apart of this point and regarding to my toptoptop... ...top.top it would not make sense to combine another (repeating) term with the TLD .top because it's a decisive point that the domain name itself is the repeating of the TLD.
So say what you want, those facts are facts and everybody knowwws it, you too.
Maybe you don't want to accept it but that's another thing and not myyy problem.