The most common Electric type move is Thunderbolt and honestly it's the only Electric move (apart from Volt Switch) generally seen outside of Rain teams.
While obviously coverage is the general point, I'd like to add one or two more points:
- Chance to paralyze
- Increasing number of Water type Pokemon
- The prevalence of lead Koko setting up Electric Terrain also boosts the move (though same argument can be used in case of Lele's Psychic Terrain, but Koko is more common lead with switch out utility whereas Lele is a wall breaker by itself)
Thunderbolt have excellent spammabillity with a maximum 24 PP, and it has a chance to paralyze. This is of great importance because most Ghost Pokemon carrying the move in the first place are offensively based, and generally fare poorly against walls and such. However, getting that critical paralysis makes it so much easier for the next Pokemon to take it down.
Further, there's plenty of Dark type Pokemon running around, and a good number of other Psychic resists (Steel and other Psychic type, both very common) that can switch in, but lesser Ground types / Electric resists. Even Electric resists (that are not Electric type) i.e. Dragon and Grass types are crippled by the Paralysis chance, Dragon even more so. Ghost moves are not so spammable as there's a good number of Dark type Pokemon running around, and don't generally have secondary status side effects.
Also, there's a lot of Water type Pokemon that are relevant in the meta that need to be threatened. Fewer Flying types now, but the bulkier Water types are annoying to deal with, so it's better safe than sorry.