No one other than Eddy Merckx is holding “The Hour Record” ! 
Whatever Zwift is just not a great tool to do real races in. Category based on FTP. 
The point is how FTP is measured?
- CP5 + CP20? Both Cp5 and 20 in one day or each CP fresh at a seperate day …?
- CP60 all the way?
- In a race with others?
- In a race against yourself, against the clock, ITT, TTT?
- Hilly, flat, indoors, outdoors, temperature, wind, elevation, … so many factors …
… f.ex. watch this:
I guess now people come up with comments like he should just train a bit harder and loose some weight like in this topic here: To cheat or not to cheat
…