We purchased a Grizzly whose owned did the same. It was all nice and shiny until you had to do anything to it. Changed all fluids, filters, and sparkplug and I was covered in WD-40 just rubbing up against parts. Maybe good, maybe not.
I did use WD-40 with dirt bikes years ago. I would spray it down before riding and the mud came off easily, then sprayed it down when wet and it kept water spots from staining the aluminum.
On the grizz, I did this years ago, but not so much anymore. I haven't ridden with anyone that gives a shit if my grizz is clean, they just enjoy the area view. If clean is important to you, spray he'r down.
Don't ever ride in dust if you spray it with WD-40. Use a good wax or lemon Pledge. It won't have dust stick to it like WD-40. When I was in law enforcement years ago we used WD-40 to clean revolvers until it start gumming up the actions when it dried.
I don't have a Grizzly (yet) but this sounds like a dumb idea to me. WD-40 is a great product, but like any lubricant on any metal surface, it will hold dust like a magnet. All those shiny chrome parts are plated for a reason - to inhibit rust. They don't need WD-40 to stay shiny. I'm a gunsmith, and I see guns owned by people like this, who think everything has to be wetted with a lubricant to protect it; nonsense. It usually means they end up with a gun that won't work, and I make some money cleaning all that goop out of it.
That being said, I do think it's a good idea to spray the metal parts of the machine with WD-40 or something similar after washing or riding through water. But the entire thing should be thoroughly wiped down with a soft cloth to remove the excess lubricant. When I do a deep clean on a gun, or any other fine piece of machinery, I clean everything completely, dry all the parts, spray with a penetrating oil like WD-40, then wipe every part with a soft cloth before I reassemble. The only parts I lubricate with something heavier are those points of contact which must slide smoothly, and then only sparingly. Lubrication is critical for any machine, but excessive lubrication is as bad or worse than none.
You would be surprised the benefits of plain old Armor All as well... I had one of those expanded metal platforms that utilize your hitch to haul coolers, etc. behind your vehicle..... I would spray that thing with Armour All twice a year and never had a spot of rust on it (Midwest winters with salt on the road and all)..... weird I know.... I have since used Armour All on everything "under the paint" on my Grizz..... dirt and mud slides ride off, keeps things from rusting and protects the plastic and rubber (cv boots, drain lines, connectors, shocks, etc.). I do use dry silicone lubricant for the electronics/connectors though.... Keep in mind that Armour All does collect dust as well but the benefits outweigh that in my case...
Armour all shouldn't be applied to anything, it's a huge dust magnet, and some synthetic rubber and some plastics don't take kindly to it. Cracking and weakening can occur. I wouldn't apply wd40 like that either, it's great to displace water, but as a lubricant, it sucks since the aerosol portion evaporate leaving behind very little lube, and the remaking additives that gum things up and attract dirt like a 4yo boy.