If you like... Before I do though I'll just say I've nothing against the guy personally, and clearly this is just my opinion; he has a successful channel so must be doing something right and clearly plenty of people don't have any problem with him; that's good, best of luck to him - inb4 I'm just jealous, butthurt, whatever... there...
As for why it's not my cup of tea... his "content" is bare minimum effort pushed out frantically in the most click-bait-y fashion possible... often making an entire video (repeating himself numerous times to stretch for that magic 10+ minute ad revenue boundary!) just to discuss a one-line bugfix on the PTR or a tiny snippet of information about an upcoming change. New hero rumored? Look forward to a video discussing the rumor, 2+ speculatory videos in the run up to the possible release, another video slowly going through every skin, emote etc. for the hero, another discussing the fact that they've been revealed... oh and of course a "pro tips for X" video despite the hero barely existing for long enough to develop such strategies... Hero tweak coming to PTR? Expect 1 extremely over-the-top "hero X is dead" "massive nerf/buff coming on PTR" "RIP hero X" video which is 10 minutes of talking about almost nothing, followed of course by another separate video showing PTR gameplay etc. You can tell he just sits down, hits a timer and tries to freestyle about the most piecemeal topic possible for 10 minutes - no pre-planning or thought at all... which is why so often you find him contradicting himself (always in different videos, but sometimes even within the 10 minutes of rambling in a single video)... for instance he'll make a video going on about how always sticking to the current meta comp is bad followed by one saying the complete opposite; the meta is the meta for a reason and you should play it to rank up... It's like he has no knowledge of his own former opinions (if they can really even be called his opinions in the first place) in the quest to create more content asap...
And onto the most major sin - his "tips" and advice are just not that good... my impression is he plays with some very very good players a lot of the time (e.g. Valkia) and although it's a team game etc. and he must contribute in some way he's not the one making the plays and not the one calling the shots... which is why his "coaching" videos etc. just boil down to him watching the footage and going "oh yeah, that was bad you got killed there"... "oh you wasted your ult there, maybe you shouldn't have used it"... rather than making any comments with real substance that show that he understands the game to a high level (which on paper he is... not that he likes to mention it; oh wait he literally can't wait to make an offhand comment about how he's GM or whatever in every video). For example - a video about how to deal with Symettra after her buff; his advice which was pretty much repeated about 5 or 6 times to span 10 minutes boiled down to "just kill her"... I even recall him saying something like "guys, it's easy just take her out, just kill her, it's that simple"... Really? Why not suggest taking a Winston or a character who can help destroy the turrets? Pharah to take off-angles and shoot the turrets from behind, and to take Sym out from range, etc? Sending flankers to hunt out the teleporter/shield-gen to take away her value?... but no "just kill her" - thanks for wasting my time... There are countless examples of this across the channel too...