Horse/flier emblem teams are amazing because mages like Cecilia or Spring Camilla can reach like 75 atk (and have more than enough speed to double most of the cast) once they have both hone and fortify on and a -blade tome. Horse emblem is particularly easy to run on budget.

The light cross pattern is weird but the thunder line, fire cross, or wind circle are often fairly likely to catch one, maybe two more targets depending on the map (try the thunder line on the bridge map). And if you hit someone with low def/res, the calculated damage is the same for everyone, which makes it possible for your next unit to finish off someone who would be otherwise dangerous

And it can't be countered, either, so it's a good way to crush a Hector (even with Reinhardt).

But it ignores weapon triangle, is that it ? I don't actually check the numbers but it's still a lot higher than a normal hit (even accounting for the 1.5 multiplier)

Also, you're supposed to plan out that strategy, don't just have Reinhardt ride up to Hector out in the open and blast him. Use other units with a similar special, you still have color advantage and terrain to take into account. I'm saying it's bad gameplay that the meta of this game is just going for open terrain face to face one round kill

Also, the AI is pretty good with support skills. It's always bunching up its units when someone has a hone attack or defense or rally anything. It's only dumb with healers because it always attacks if someone is in range, so the healers on horse end up on the frontline, but on support, it makes the most of everything.