What’s up with dog trainers’ favorite small dog?

I'm always looking for small dog training videos for tips and breed research because I'd like my next dog to be significantly smaller than my current dog and I've noticed something a little weird.

I know what the typically trainable small dog breeds are:

Poodles, bichons, havanese, papillons, poms- but those are almost NEVER the dogs trainers have lol

If the trainers do agility they probably have a papillon. But if it's anything else- they have a chihuahua doing obedience training.

Like I want to say 70% of good small dog training content I find is with a chihuahua. What's up with that? Are they super biddable or something?

Do you have a different experience?