A more apt analogy would be to use the truck bed size. Horsepower is more akin to the CPU speed.
Most people don’t fill their truck bed just like most people don’t fill their RAM. I’ve had no issues with my family users who just do typical light laptop tasks on 8GB RAM. I think the memory upgrades need to be much, much cheaper, but 8GB works absolutely fine IME. I would like 16GB but it’d be a waste for the other users in my household.