They also broke the security on the default configuration because now you can just interact with the system components to bypass UAC, see e.g. [0]. This is officially not a security vulnerability because UAC isn't actually a security barrier unless you set it to "Always prompt", but just a feature to make applications play nice. But note that it's not on "Always prompt" by default...

[0] https://github.com/hfiref0x/UACME

Then Vista must have been completely unusable in that sense. Because 7, 8.1 and 10 that I occasionally use are still very bad compared to sudo.