even though everybody knows what it means right away
You're missing the point.
When someone says, "The new battery is ten times smaller than the old battery," yes
But there's a reason those are TWO DIFFERENT SENTENCES.
When you use the word smallER in that context, you're communicating that the old battery is small, and the new battery is even smaller. Why? Because you're saying that the new battery has time times the smallness of the old one. That has a completely different connotation than a sentence that suggests that the old battery was what it was (or was large), and the new battery is comparatively small.
The reason we have lots of vocabulary words, adjectives, and constructions is so that we can be nuanced and more precise in simple communication. When you use a sentence that essentially forces the audience to go find out what you actually meant by "ten times smaller" (was the old one small, or huge?) then you've done the opposite of providing useful information. All of that in order to avoid using slightly different words that we also all know?
This is pure laziness, that's all. It's mimicking a sound or phrase without thinking about what's actually being communicated. It's no different than people who say, "I could care less," when they mean exactly the opposite. They are uttering sounds without thinking about the actual words they're using. One small, lazy spoken step for man, part of one cumulative giant leap towards dumbing everybody down.