Is kog'maw out of meta or just really weak?

ATM there is 4 ADC (ezreal doesn't count) magic DMG AA in the game (kaisa,kog maw,varus and corki). 3 of them deal on hit DMG always applied and on a flat way. Kog instead need to use his w (18 s of CD with 8 s of duration) into %hp DMG. Kog kit is designed to counter tank through botrk and guinshoo. Tank actually are out of place (Due of the high amount of true dmg) with the exception of Sion and galio which prefer bruiser build instead of tank one. Jungle is pretty dominate by assassin or diver which mean a hard life for kog early-mid game. Support meta ATM is all about catcher and poke mage which both of them doesn't really fit into kog maw ADC fantasy and also are terrible match up for him (due to his lack of mobility). Countering kog maw kit is easy for multiple class (as tank/bruiser u need tabi+adaptive helm and as squishi a maw or a build in DMG is enough). Kog maw lategame look too weak compared to other lategame ADC such as twitch,jinx,tristana,and even caitlyn which provide more dps having a simil and kai'sa and vayne which provide self peel tool and anti tank build. All of them (maybe not cait) are way stronger than kog maw into both early and lategame this is by the fact that kog maw power is all about W and base stat. Kog'maw kit seem to not working at all for his adc playstyle. His passive make no sense for both of his playstyle (ap and ad) as a long range ADC he need to be far from his target and as artillery mage he need to sniper from far with his E and Ult. His passive actually required to stand close to the target which is counter intuitive and need an overhaul rework. His Q is a Ok tool for his Ad playstyle but it could be better. His ap playstyle kinda work but a lot worse. It's just an aa amp steroid that require to aim but at least work. The W ap ratio is really bad for Ap kog maw which usually tend to be a wasted spell and for ad kog maw is basically his main dmg spell. Kog maw E is too weak in all the phase of the game. As is only defensive tool, his E slow is so bad that people usually tend to get it at lv 4 or never unlock it. Casting into later phase of the game where the number on it is good enough mean a lack of dps which turn him into a death trap. Also his E isn't helpful into most scenario with all the poke and all in oneshot that are into the bot lane. His R is just ok for ap kog and weak efford for ad kog maw. Ap uses it for log range poke while ad use it for last hit minion from far or last hit kill. At least it has an AD scale which mean that it can scale through the item stat rather than most of his kit which scale better with item power (guinshoo,botrk,wit's end). The lack of Ad steroid or physical dmg on his kit make kog maw a worst pick compared to other mixed dmg carry (kaisa especially), the lack of self defense and Cc make him too reliant on enchanter support and the lack of tank make him not fitting is job. So in conclusion what's your tough about this adc (or apc) he's weak overall or it's just the meta, or maybe i'm wrong somewhere?