It is rarely used in ranked games. Even if some decks in Duel Links require having a good starting hand to set it's tempo, "Switcheroo" has the upper-hand which gives you an option to retain cards and reshuffle an unwanted card for a specific scenario. In general, using this skill is unreliable, but might work just fine.
The fact that most other tcg have a mulligan in the game and some even allow multiply mulligans and this takes up a skill that can be filled by free cards in general, and other free advantage that is far more powerful then this.
what is the better legendary duelist to drop this skill?
I guess that he wrote that before Balance was changed (after reading this page, I would go for Balance over Restart most of the games). However, I wouldn't go as far as to say Switcheroo is better than Restart, not in a million years.
Kaiba can get restart ?? I dont get it yet after playing and use him like 5 months :(