No the limitation on how much you can buy is very much to prevent deliberate overdose or attempted overdose.

Ibuprofen is hard to overdose to the point of fatality, but other drugs are already limited (like Paracetamol) and if Ibuprofen wasn’t limited people could try that and end up causing huge damage to their bodies even if they don’t kill themselves.

The law limits how many packets people can buy in one transaction. There is no way to stop people going multiple stores to stockpile or to keep buying them every two weeks. It’s not effective at combating dependence.

It’s really not really aimed to preventing people overusing the medications. It’s just a way to try and prevent impulsive mass purchase with the aim of suicide attempts. And it does work on a population scale at reducing harm.

For example the classic ED attender of a young girl who impulsively take 2 packets of paracetamol as a cry for help is well served by this law.

Edit: worth emphasising too - you can get many more in one go on prescription. This is very much about over the counter purchasing.