And how many people are going to involve some third parties instead of just tossing the item and buying a new one?
Current EU-system, the seller is always first point of contact in case of defects. So the seller should involve a third party and then share costs (after 5, 10, 12 years depending on reasonable durability). So the market for third party repair isn't a consumer market!
The only products I know third party repairs exists are: cars and household appliances. And even for household appliances the above holds, much goes via the seller. That it doesn't hold for cars is, I imagine, mostly lobbying. Even there collective consumer action is on the rise.
Then there is an additional problem: technical progress. Having recently replaced many household appliances (mid-30s now, so everything was 10yrs+ old), my machines use 30-40% less energy (from A to A+++). I'd be an economic fool to keep the old machines. Law requires the supplier to take care of the waste, so I really have no incentive to keep the old machine in use.
I'm a big proponent of 'right to repair'-rules BTW, but think they do not add much to the bigger picture. Pricing of household appliances as a function of the running costs have fallen dramatically. So repairing just makes little economic sense. The environmental impact, I'm not sure. I guess 100 kg of waste is a lot more damaging than a few thousand KWhs. But that all depends on the way disposed machines are treated. Cradle-to-cradle could make a lot bigger impact than right-to-repair imho.
However, I do know of people who fight for their rights as consumers as a matter of principle, and I actually applaud them. They do a good work for the commons.