We shouldn't expect the ability for Steam to honor a request to remove our accounts because that ability could be abused by family conflicts, friends and jokes?
Yes because it's nearly impossible to check if it's actually you request removal and not somebody else. Otherwise Steam would have to keep your account data on servers anyway so there is no point in removal procedure.
Considering Steam don't ask about any of your personal information (and you can pay using PayPal or even "offline" wallet codes) I would suspect that such feature will be used more for harm than good.
Wait, why do we need special requests for Steam account removal? I would login and delete my account (and as a result immediately logged out I suppose). Steam uses two factor authentication for login and unless someone has got hold of your Steam password and email password, you should be safe.
And what happens when you want to undelete your account, because it was deleted by someone else who had access to your computer? (This will happen)
Would deleting an account enable the associated Steam keys (physical or electronic) to be reused? Or is deleting an account equivalent to putting all your games in a pile and burning them?
Two-factor authentication with email doesn't actually help to average user at all. When Steam account password is stolen then email password is likely too.
Valve is known for asking for PII for things such as recovering accounts that have been hacked (to wit: fax in your driver's license or other photo id and a physical CD key from one of your registered games)
In same time Steam support accounts are completely independent from Steam store accounts. Anyway my point is: Steam is not dating website or social network that collect tons of your personal information.
By not having account deletion procedure they don't hurt anyone's privacy, but just save average user from one more possible pain in ass for no reason (because they wouldn't be able to delete accounts for real anyway).
For majority of users who use any kind of ingame purchase (dota, TF2 hats) - Steam stores credit card information etc. I know one can pay using Paypal but I dunno how many users use that option. So, Steam does store personal information of users period. It is not very different from any other service.
On other hand, allowing users to delete their accounts can help with kicking serious gaming addiction. It usually takes time before you can level up a new account for playing at skill levels you were. Part of me thinks, Valve does not allow deletion of accounts precisely because of this.
Saving of credit card information is optional on and it's can be removed with one click. There no big difference between trust service that it's going to remove this data or whole account.
And idea that some people going to remove somebody else account to "help with gaming addition" is good reason to not implement removal.