I don't think that is true. I haven't used Windows in years, but in the past I have talked to Microsoft support on the phone, as an individual without a support contract. To check that it is still possible, I went through the IT professional and developer support flow [1] and ended up with a button that said "Contact Microsoft. Have a technical support representative contact you. Start request". So it is at least possible to contact them, though maybe it isn't on the phone anymore.

If you are a paying enterprise customer of Microsoft you can get very good support. I briefly worked for a company that ran their compute infrastructure on Windows (~2000 physical servers), in the month I worked there they had multiple tickets open with Microsoft. If I remember correctly, one was for excess memory usage and Microsoft dug through a memory dump to find the problem.

I hear Google has improved for paying enterprise customers, under Diane Greene's leadership, but they certainly burned some bridges in the past with poor support.

Public bug trackers are super helpful for professionals, but the lack of one isn't necessarily an indication of poor customer service.

[1] https://support.microsoft.com/en-us/assistedsupportproducts