That statement is not entirely correct.
It is true that reverse is not synchronized, however it does share the 5th gear synchro so if you damage the 5th gear synchro you can sometimes lose reverse and/or 5th gear. Ask me how I know this.
First things to check are the attachments from the shifter to the trans. Make sure there's no slop and everything is tight. Check your boss, make sure it's not broken.
How do all the other gears feel? If they're just as stubborn you could have some broken fingers on your pressure plate. Reverse is typically the first gear to show signs of damage but when it starts to get really bad all the gears will be stubborn to get into.
How are your motor mounts? Is there any slack in your clutch cable? How old is your clutch/pressure plate/TOB?
Other than that, I'd say something is wrong internally.
The reverse lockout mechanism keeps the transmission from being shifted into reverse from 5th gear only. I've never seen one broken before, I don't see how it could break actually since it's spring loaded and only moves in one direction. However, I never say never and I suppose if it did break that it could cause some issues with getting into reverse.
Chayes, I'm in Michigan also so if you need any help just give me a shout.