It hasn't been 2 1/2 years.
Also - the major issue with this sentiment is this:
The general consensus was that Kassadin was useless and weak. Until he exploded out of nowhere into 100% pick/ban after seeing some good play on the pro circuit, and then stuck their nerf after nerf.
People also thought the same thing about Orianna, Lee-Sin, and Lucian. Before they exploded into being the single best champion for their lane.
As far as GD is concerned, champions only fit into 1 of 2 categories:
- The worst champion ever that's never played.
- Completely broken and OP, see them in every game, should be gutted completely, Q_Q
And again - when Kassadin was far stronger than he was during most of his pro-scene run, people thought he was useless and weak.
If you don't have 30 games on a champion, you're probably going to suck with them.
Especially if there not currently dominating the meta - your allies are going to be much less aware of your strengths and weaknesses, they're not going to work as well with your specific champion, you aren't going to get rapid iteration on what works and what doesn't by also facing the same champion you're trying to learn and seeing what works for them, and your optimal build/level-up pattern isn't going to be common knowledge. You mostly have to figure out a lot of the movements and footwork yourself.
And with a small buff - Kassadin could easily be pushed into a place were the pros feel solid about using him, he become meta, and everybody suddenly knows how to obliterate things with him again.