Laptops used to work that way in sleep mode. Microsoft decided to make a change to the specification some years back that, long story short, makes the CPU draw significantly more power in sleep mode. Many of today’s CPUs apparently don’t even implement the older, more power-efficient sleep design anymore.
If you want details, look for “S0 Modern Standby” vs “S3 Sleep.” Be warned, the topic is very confusing.
The top part of this thread might help explain parts of it.