Case in point: The enforced standardising of mobile phone chargers has given consumers more choice of chargers to use with their phone. Thas proven quite useful in practice, e.g. when they leave the one that came with their device at home because they didn't expect to need it, or when the manufacturer's own brand is more expensive than an alternative, or if they have an old phone.
I remember before USB-C standardised phone power, when visiting someone the chance that they had a power supply you could use was very low, because each one used a different connector. Even different models from the same brand. If you went travelling at short notice, you might have to buy a second charger just to keep you going for a few days. That's no longer required. Over the years you would end up with a box full of incompatible chargers, all e-waste. I think I have about 10.
This particular consumer benefit didn't happen voluntarily among manufacturers (unlike, say, SIM cards), so forcing it has increased consumer choice in some useful respects.
I prefer Apple's lightning connector (even though I don't have an iPhone), and other connectors better than USB-C would surely emerge if allowed to, so I do see benefits in not enforcing a standard like that too strictly. But the situation before USB-C mobile power was less consumer choice not more, for consumers of almost every phone.
Standardisation of the former means we don't have to have half a dozen sockets on the wall because every domestic appliance manufacturer uses a different design plug... or have each of those sockets provide a different voltage because every appliance manufacturer opted for a different voltage.
Standardisation of the latter leads to waiting 15 years for your Trabant.
You gain choice of charger to use with your phone, which most people do want, especially when outside their home.
Although it's not the most important thing in the world, forcing standardization through law is the opposite of giving consumers choices.