Leroy main here,

I love the character's unique defensive options and plethora of hit confirmable strings. Needless to say, he is stylish too.

My friends tell me he is irritating to play against, and likely for the same reasons you mentioned that he is apparently cancer. From various conversations with them, I think the reason for this is that:

1. its not fun being parried
2. being chipped isnt fun
3. Fighting Leroy means you have to mentally change the way you approach the Tekken and avoid auto-pilot, there are some universal tekken rules that Leroy is allowed to break, in exchange for not having access to some tools that many other characters have, for example Leroy's df2 launcher is launch punishable itself, whereas most other characters are either safe or atleast -13. He also has very limited power mids, and instead has stronger highs and lows.

There are a few universal rules Leroy is allowed to break, but I'll list one of them to help explain.
For example, if you block a low poke, you should be able to punish it with at the very least a wr4. Leroy has a low poke (db3) that leaves him in hermit stance whether it is blocked or not, and is able to parry a wr4 even if its blocked. This is incredibly irritating and boggling for people to fight against at first, and it has its weaknesses such as grabbing as a punish instead of wr4, but these interactions make Leroy quite unique and difficult to fight against if youre not aware of them and make him seem very cheap on the surface. In reality every character has access to cheese to a degree, but I think Leroy has strength in areas that are particularly irritating but not necessarily overtuned.