Not too long ago Riot Blastoise bragged about a graph illustrating Singed among other niches having the highest learning curves in the game statistically. Mastery over Singed's W is a big part of his extremely high mastery curve.
What the prospect of its secondary effect (to seemingly occasionally glue people) seems like to most people and it being inefficiently used.
What it can be used for when fully mastered [setting up sure kill combos/ganks, anti-dive, saving towers/obj]
What happens when bugs aren't addressed specifically against Master Yi, spitting all over the mastery curve.
Considering he is unslowable as well, the sign of a good Singed would be to obviously properly land the combo on him, but the fact he is bugged to be unable to be rooted means there is absolutely no way to peel or fight back vs the champion and if he catches you anywhere on the map you are dead. And funneling is even being reintroduced if those clips are any indication, further demonstrating a spike in the champion's popularity. This is not a minor bug or something you see once in a while, this is something actively undermining an entire champion and is very visibly active.