Many weight gainers today are not that bad. I have used one and did fine with it until I started drinking 4 of them a day because I didn't have time for real meals.
I have never been one of those who acts like all weight gainers are evil. They aren't. It is simply that learning how to eat real food will no doubt teach you more in the long run when it comes to what you really need.
I would leave weight gainer use for: -those who plan on packing weight on quickly like after a major weight loss. This could make sense for someone rebounding after an injury and time off if they lost muscle...or maybe those who have dieted drastically. -Those on steroids -Those with very small frames who would benefit from just more overall body mass and strength gain. -Those with very fast metabolisms who can lose any extra weight quickly.
You shouldn't be thinking of a weight gainer if your body fat percentage is hitting near 20.
Weight gainers get a bad rap from people who don't workout hard enough to warrant the extra calories. If you don't workout hard adding an extra 1,200 calories from a shake WILL make you add fat mass pretty quickly.
Read the label though. The cheap ones will probably have a lot of sugar and fillers. Where as the more expensive ones won't.
Just a heads up...but bodybuilding isn't really about "health" at its core. If you want to eat more oats, then do so. As far as bodybuilding, however, it is more about what you respond better to in order to gain muscle.
Your question is a little broad. Some weight gainers like the one you mentioned are nothing like the mega-sugar drinks of the late 80's and early 90's. Back then, they had 2,000calorie shakes with nothing but a shit load of sugar.
I remember drinking one that was so sticky from the sugar your mouth would stick to the glass.
Weider had one where he claimed you could gain 14lbs in a week!!!
So I did!!
But I stopped being able to see my toes!
So yeah...your oats and whey may be "more healthy" (whatever that really means). Weight gainers are a shot gun approach....and yeah, sometimes you need a sawed off.
Weight gainers are simply protein/carbohydrate blends. They are a handy supp to take post workout for recovery. Surge recovery & others on this site are "weight gainers". I'm a sprinter with no intention of gaining weight and I use half a serving of "weight gainer" post workout purely for the fast carbs & protein.