Nope I don't consider majority of that true gaming at all. Mainly due to majority of the games are not complex. Those are something you play when your brain dead and don't need any kind of skill to play. So something to kill time. So those are casual games.
True gaming are the ones where you need to think at a certain level and have to have some kind of skill. So basically anything were the game is more complex.
Phones and tablets do have some very good games that being said if you just play on a phone or tablet they should not be considered a gamer. Games on mobile devices are designed to be time wasters and not much elts. However there are many games like xcom knights of the old republic and several others that have been ported to mobile devices. No one says hold on I'm gaming on my phone. Everyone says hold on I'm playing a game on my phone.
Well the fact i can play any retro game. - Final fantasy - A Deus ex game - gta, max payne. - minecraft - and a few games with stories. I'd say people play games on ohone or tablets are no different. Just the type of games you play. Then again i spent hours straight playing Crossy Roads a few times too haha. Honestly i can have good fun on phones but i love my 3ds too.
It is gaming, but I do not really consider the people serious gamers per se as they just do it as a casual time-killing. Just like someone is not a serious movie-enthusiast for just watching youtube videos.
Yes, in my opinion. It's true that the a lot of mobile/ tablet games are casual no-brainers, but there's an increasing number of games up there that require mental focus and/ or serious commitment. Also, there are those who prefer playing mobile versions of games that are released for PC and Playstation as well. Those games don't exactly stop being what they are just because it's a different platform, you know. :P