Completely agree - I always thought the framing of "exercises" is the right one, the point is that your brain grows by doing. It's been possible for a long time to e.g. google a similar algebra problem and find a very relevant math stackexchange post, doesn't mean the exercises were useless.
"The fact that forklift truck can lift over 500kg should tell you how worthwhile it is for me to go to a gym and lift 100kg." - complete non-sequitur.
If the judge of your fitness took into account only the amount you could lift, then sure, why not use a forklift.
This is what's happened in education. The education system is not concerned with teaching you to learn, or even teaching you, it's concerned with grades.
As many have stated here, homework is practice for the student, and can be helpful in learning. However, it's given out as something to grade without any collaboration on the learning experience.
By the way, I'm ranting about all this as someone who did very well in both high-school and university, so I feel somewhat justified in calling bullshit on the whole thing.
"The fact that forklift truck can lift over 500kg should tell you how worthwhile it is for me to go to a gym and lift 100kg." - complete non-sequitur.