Well, ABS has been around for 50+ years, in common use for 35+ years and mandatory for the last 21 years, so it is hardly new technology. And yet even into the early 2000s, nobody changed it regularly. Then - whenever it was - late 2000s, early 2010s - suddenly every dealer started recommending it be done every 2 years EVEN THOUGH it is not required by the manufacturer's service schedule. Hmmm.... somewhat strange that, don't you think...?
In the very long term, yes you might get corrosion in the braking system, after 10-15 years, although split rubbers/seals are also a contributor here, so how much is down to the fluid is debatable. Then again, the lifespan of your ABS pump is probably no more than that anyway, with modern low standards of engineering.
Boiling brake fluid, which people used to fear, is a complete thing of the past. The most common effect of not changing the fluid for a long time is poor brake feel.
Few people keep their cars that long, many people who bought a new MG EV will replace it after 3-5 years anyway, some sooner. Yes, some may be going for 10 years plus, so perhaps it is worth it for those?
No, there's no harm in changing it sooner. But where does that end? Why not change your coolant every year in case it fails? Why not change brake pads after only 50% wear or change your tyres at 5mm, etc... etc...
If you've endless amounts of money, feel free to change everything as often as you like, but I still think this one is a scam. I respect that you don't agree.