Renowned body builder, Ronnie Coleman, knows about muscle hypertrophy. He also knows about light weight.
Sure, this isn't light weight. And he's using it as a motivational tactic. And light weight won't win you a Mr. Olympia.
But...
Studies Show...
Ah the two words that help us win arguments...
A recent study showed that we only need to lift greater than 40% of our max to increase muscle strength and size.
"lifting very light loads (20% 1RM) is suboptimal for hypertrophy, but training with loads as low as 40% is just as effective as using heavy weights" -Brad Schoenfeld
it's also important to note the improvements at 12 weeks versus 6 weeks. physical improvement takes patience. (image source)
It's another study that shows that volume is more important than load.
We only need to lift 40% of our 1RM to make gains.
Why is this relevant?
I've written about it before (read here). But in summary it's safer and more applicable to the general population.
Why take a risk and make things more difficult? Using heavy weights for hypertrophy is like going to your local coffee shop for the wifi. It's not secure and not efficient.
Summary
It's more about intensity and volume rather than the weight itself.
So lose the ego. Drop the weight. Increase the volume. And get some safe and efficient hypertrophy.