Microsoft isn't entirely wrong, and "right to repair" advocates conspicuous failure to acknowledge this tradeoff is one of the weaker and more irritating parts of the movement. Note tradeoff as the word, it's not as if good things don't come with it too, nor does it mean the same weighting applies to everyone. It doesn't mean that those who want to shouldn't be able to hack on their devices. A similar tradeoff applies to pure software signing, where I am very much in favor of a legal requirement that hardware "possessors" [1] should be able to load their own master signing keys into any cryptographic roots of trust, and thus be able to run software of their choice with no further relationship with the manufacturer even in a system that has full signing required.

But the power to do that is also the power to screw it up. If any 3rd party can repair something like biometric hardware, any 3rd party could also compromise said hardware. Some people may find the benefits of the former outweigh the latter, but I do think it should be a choice in the law, and that liability should adjust accordingly. Ie., you can upfront on buying a device request that it not enforce cryptographic reqs for hardware repairs (this could be controlled by a permanent fuse or many other ways), but alternately you can also request that continue to be a requirement. In my case for example I do not want to buy an iPhone that is "right to repair enabled". I don't want the magic circle of who can mess with it expanded any further than the minimum, which is Apple themselves who are by definition inside the tent anyway.

I also think the "right to repair" movement is a symptom rather then cause thing, and obscures the real problem for the vast majority of the market. The true core issue is that, in America in particular, legal standards for fitness for purpose are simply way, way too loose. The reasonable expectation most people have for buying something expensive is that it'll be in working order for a proportionate number of years. Not forever of course, but a $200-400+ bit of electronics shouldn't be dead in 13 months either. A $500-1k one should probably last at least 4-5 years without further cost, etc. The retail price should reflect whatever it takes to make that happen. Manufacturers are the ones in a position to deal with that, who have the best stats on failure rates, and can make decisions about tradeoffs between cheapness of repairs, more on QA, where more expensive repair reqs might reduce repair need even farther in the first place (or provide other feature value), etc. It simply shouldn't be the consumers' problem at all, beyond evaluating the retail price. Yet it's completely standard to have something ludicrous like a single year warranty.

Essentially, it's a classic market Externality problem. Everyone does expect their devices to last, but are forced to roll the dice on whether they specifically have bad luck and have to pay expensive rare repairs all by themselves. The manufacturer gets to advertise an artificially low price but externalizing the failure rate percentage onto the customers, and even charge extra for what should be standard. Instead warranties should be adaptive, something like "1 month for every $12 retail price up to a maximum of 5 years" say. Then let the market sort it out from there. I'm worried "right to repair" will ultimately be camouflage that let manufacturers skip out on their real responsibilities in some cases. Right to repair could make out of warranty repairs cheaper, but you shouldn't have to pay at all within a reasonable normal life.

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1: which would be defined as something alone the lines of "anyone who has paid, either upfront or on an ongoing plan basis, for hardware and possesses the right to control access to it." Lawyers could make it watertight, but basically a definition which would explicitly not allow any sort of "oh we were only leasing it to them!" loopholes.