I'd say the reason the YGO Abridged Series is so popular is because it's the original Abridged Series. It was the first one done, and it's been continuously well done ever since it was created. It tends to draw a lot of fans, even those that aren't as familiar with the YGO fandom as those who had been with the series since the start. littlekuriboh was insipired by the community playthedamncard, and all other series afterwards, for different animes, were inspired by littlekuriboh's creation.
Also, while the series features a lot of memes and such, it's created its own memes (such as the "screw the rules..." or "...in America!" lines). There's a lot of other things that the YGO TAS has brought to both the fandom and the internet in general that would simply take too long to explain in depth. And this is all considering only one guy does practically all the voices, editing, and writing.
Suffice it to say, YGO:TAS has done what a lot of other anime parodies have tried and failed to do. And it's the original that started a whole new genre of parodies.
*cue "The More You Know" theme music~*
Also, while the series features a lot of memes and such, it's created its own memes (such as the "screw the rules..." or "...in America!" lines). There's a lot of other things that the YGO TAS has brought to both the fandom and the internet in general that would simply take too long to explain in depth. And this is all considering only one guy does practically all the voices, editing, and writing.
Suffice it to say, YGO:TAS has done what a lot of other anime parodies have tried and failed to do. And it's the original that started a whole new genre of parodies.
:)