After a few incidents with front wheels coming off due to the studs holding the spacers on snapping off. Nobody I knew ever used them on the front wheels again.
That was back then. The materials are probably much better now then in those days but I personally would never put them on the front wheels. When properly installed on the rear wheels I have never heard of a problem.
An old racer once told me it is because the front wheels turn and cause to much side pressure when turning at speed causing the spacers to crush just enough for the lugs on them to come loose. I don't know if this is true or not but it does make a lot of sense to me.
Anyway, Most guy's would use the spacers on the back wheels to use wide, wide wheels and tires but did not want or need them on the front because the skinny front wheel set-up was in vogue at that time. You could go to the speed shop and order wheels that were a different size for the rear and some off-set wheels for the front that looked the basically same. I guess you can still do that. Creiger was the one's of choice back then. They had all sizes and looked good.
Some street rods still need to use spacers on the rear wheels so the tires don't rub the body. Depending on what wheels the owner likes because they don't like the very deep dish look but need the space.
The big secrete is just to buy quality spacers, Use Blue
Locktite and get a torque wrench to tighten the lugs holding the spacer on to 100ft-pds. VERY IMPORTANT
after installing them and you drive for 50 to 75 miles. Pull off the wheels and check the torque on the spacers. after doing that, You will never have a problem.
Do NOT use locktite on the lug nuts holding your wheel on.
As for this:
"NOTE" Spacers larger than 1/4" are intended for rear wheel use only."
I would think the old racer was on to something and I would not use any spacers on my front wheels at all.