I would suggest you use as strong a receiver and cradle as possible to minimize the chance of damage to either.
There is no way to say what is the perfect pull and what the capabilities are for every situation. I would not be afraid to pull mine 90 degrees to the side if I needed to. Could that stress the frame? Sure. Weigh the risk vs benefit. Is a straighter pull a better choice? Yes.
This boulder needed to be cleared to open the road out.
A straight pull was not possible. Using a pulley and some distance we were able to pull it off the side and roll it down the valley safely.
Class III hitches can be rated to 10,000# (weight distributing) but may be as low as 3500#, Class V may be 18,000# . Keep in mind those ratings are deceptive. It is rated for highway use pulling a load attached to a ball. The hitch is rated for tongue weight much lower than the load. That is a no-brainer. The strength of the hitch is not for loads applied downward. Think about pulling a heavy load and the forces applied. Use that as consideration when rigging a pull. This applies to all mounts, receiver and frame mounted. A side pull can tweak the frame of a vehicle in either case.
If you are a hardcore mudbogger, or rock crawler, then a receiver mount winch is probably not for you. A frame mounted winch plate is less likely to harm the mount and has less leverage on a side pull.
Having the ability to pull through that snow drift, mud hole, or slip off the road has been priceless to me. Even used for a little yard work.
Not having to pack it every day on a daily driver is huge to me. It can sit in the garage out of the weather when not required. I carry a set of booster cables that use the same connector as my cradle mounted winch. That allows me to use the winch in the receiver of any vehicle. I also have a receiver mounted to the front of my car trailer. The winch can be used there to load a vehicle. I have probably used it there more than any use.
Lots of options. That works for me. Having the option to winch backward out has value to me as well. Sure I could rig a rear pull, but putting it in the rear receiver eliminates lots of work.