Should I pre-season meat with salt even if it's skinless?

If the chicken is not left exposed to the air (see below), then seasoning ahead of time will not dry out the chicken; in fact, it will do the opposite. When salt is applied to the surface the osmotic pressure differential (the difference in salinity between the inside and outside of the chicken) will draw out moisture at first, then the salty water will be drawn back into the chicken, helping to break down muscle fibers and season the chicken inside.

You will lose less moisture when cooking, and your chicken will be more tender, moister, and better seasoned.

This is also true for steaks and other fleshy comestibles. The use of salt is a complicated subject and there has been a lot written about it. Unfortunately, there is a lot of false information out there, even from famous, professional chefs. For example: whether to pre-season eggs for scrambled eggs or not.

I have done my own tests with seasoning and also read a lot on the subject. One thing I found, for example, is when sous videing chicken, white meat and dark meat behave differently with regard to pre-seasoning and need different temperatures and different lengths of time. In the case of white meat I find it comes out better with no pre-seasoning, and with dark meat, which I sous vide for longer, the affect of pre-salting becomes less pronounced the longer you cook it for. I do my dark meat for eight hours.

If you are going to pre-salt, do it at least 45 minutes ahead of time. If you salt a steak, for example, 20 minutes before cooking it will be worse than salting right before cooking or an hour before cooking.

Note: Dry aging of meat and poultry can be done at home, and in this case you want to leave the meat unwrapped in the fridge. For example, when I make a whole turkey I spatchcock it then dry brine (with salt only, no liquid) for three days covered and then one more day uncovered. This makes really crispy skin and the salt gets deep into the flesh for better seasoning and moister turkey.

I could write a book on this subject, but fortunately, people much smarter than I already have. I suggest you read Harold McGee and Kenji López-Alt's books as a start.

I wouldn’t season skinless chicken anything With salt for that long as it does draw out moisture and will cause your meat to be dry, along with partially curing it, per your example anyway. With marinades it really depends on what you are using. For example, if I marinate beef bulgogi I slice the meat very thin allowing the marinade to penetrate the beef. For chicken, you can tenderize to keep whole or slice, then marinate to do the same thing.