HTupolev

Usually they're not, but there's no reason they can't be. With current typical chainstay lengths, tire sizes, and crankset q-factors, many road bikes don't have a lot of technical reasons to be unsuitable for fenders.

I really dislike the widespread attitude that fenders are somehow unsuitable for performance builds. It's an attitude that results in people building bad rain bikes that they dislike riding. If you build a rain bike with the intention of it riding well, and you equip it with supple nice-rolling tires, and you use quality fenders and mount them well... there doesn't have to be much difference in feel and performance between that and an unfendered road bike.
I don't think of my fendered bikes as "rain bikes", since I regularly ride them in sunny weather as well. It's more like the non-fendered bikes are "sun bikes", messy if used in wet conditions.

Touring bikes tend to involve a variety of compromises to accommodate heavy and bulky rear loading, both in terms of geometry and stiffness profile. Even unloaded with lightweight components, they're generally less lively and significantly heavier than a performance road build. Getting one just for the sake of having fenders would be pretty weird.

I sometimes use my touring bike on rainy road rides for the sake of variety, but it's not how I'd do a wet-weather performance road build at all.