Besides, at enterprise scale, how do you trust internal teams? It could all be security theater and they aren't delivering on their promises as well.
MS remote attestation doesn't require remote cloud or anything like that, I recall it supporting air-gapped environment from the start (guess why, the top-price enterprise clients want that, including resigning windows with their own secure boot keys).
Disclaimer: for various reasons open source remote attestation in corporate is currently on my roadmap at work
Some parts of it maybe do. Some others, like multiple different Azure teams, don't even think about anything resembling security, or there wouldn't have been multiple critical and trivially exploitable security vulnerabilities on Azure in the last year only. (If you don't know them, please read up on them. Security is hard, but in those cases nobody even pretended to try!)
And yes, there's nothing evil involved if they are owner controlled, something that honestly was heavily Microsoft pushed because they do have clients that insist on them - the DRM functionality in intel ME has keys controlled by broadcasting associations instead (this is why you can't stream HQ on Linux from official sources), same with part of why AMD PSP got some uncontrolled bits (the blackmail goes that if you don't do that, customers will quickly find they can't stream netflix/whatever in high quality on your hw and will stop buying it).
Personally I believe that owner-control of hw should be enshrined in law, just like right to repair and modify, along with laws against deceptive "looks and quacks like a sale, is actually a lease" practices
Have you seen OCP's Caliptra RoT, which requires OSS firmware, enforced by dual-signing of firmware by both OEM and owner? Currently for hyper-scalers, but this approach can be adopted by other enterprise customers, https://www.youtube.com/watch?v=p9PlCm4tLb8. Attestation will be done to Caliptra, which can then release SoC boot ROM from reset.
The managers who want remote attestation aren't the people implementing it. They either pay someone else to do it, or they pay someone else to do it. The difference between paying a third-party company and an employee is that employees are more expensive, because the costs aren't amortized over other customers who want the same stuff. Why would they be more trustworthy? Why would they be better at it? Why would it be any less likely to be hacked if you did it at your company than if you outsourced it?