Its far from a bad admonishment and I'll explain why.
Headlight aim is just one factor to take into consideration when you switch out the bulbs. The aim is rarely off either way if it's stock because aim isnt affected by driving and vibration. What affects aim is when you remove the entire headlight housing and install a new one. Replacing the bulb has no effect on aim.
Secondly, a brighter bulb in place of the stock bulb means you'll have too much light in certain areas where there wasn't meant to be that much light. This will cause a patchy light pattern.
Thirdly, some cars have squirrel finders(lights that light up signs) built into the projector. If you put in a brighter bulb, this squirrel finder will increase in lumen intensity and, as a result, blind others.
Lastly, messing around with the aiming of a headlight without proper equipment and methods is surely the quickest way to misaim the headlights for a layperson, causing one to blind others or not get maximum performance from their headlights(by underaiming)
In short, everything becomes out of spec when you put in the incorrect bulb.
>the aim is rarely off
Having owned more than a fair number of vehicles for someone my age, and been responsible for several more through various employers, I'm going to stop you right there.
Appropriate/correct headlight aim is
The Exception not the rule, by a mile. even in a new right off the dealer lot. Even in states that require motor vehicle inspections, headlight aim usually comes down to "do both lights work high and low? If customer says they can't see -Crank Them Skyward. Customer complains of flashing: -Aim Them At The Ground.
>replacing the bulb has no effect on aim
Can also be incorrect. Correctly inserting the bulb, which is usually very easy to identify in a pass/fail manner, with an in-spec bulb of the correct (or appropriate substitute) type
should not have an effect on the aim.
>brighter bulb ... too much some areas... too little others... patchy beam pattern...
Incorrect. Now, if you go sticking a completely correct bulb type, e.g. substitute a h13 for an H4, or a H2 for an H1, etc etc etc...
With the recommendation to substitute the 9011/HIR1 bulb for a 9005 bulb, or a 9012/HIR2 for a 9006 bulb, situationally an H9 in place of an H11, etc... we're talking about bulb types that are effectively compatible. In the HIR1/HIR2 situatiom, these bulbs were literally designed to be a completely compatible replacement type bulb. H9 for an H11 has a higher output, higher intensity filament that is placed in the same position as the H11 filament, the bulb bases are compatible with minor modification, and the H9 does not present auch an increase in power draw as to present a risk to an OEM electrical circuit.
>some cars have squirrel finders
All headlamps are required to have a certain range of light above the hprizontal low beam cutoff for signage and road illumination. Squirrel finders are principally found in Halogen projector lamps only. Typical HID projectors do not have them at all. The small increase in extra output from swapping (appropriately, as the bulb was designed) a 9011/9012 for the older 9005/9006 is not going to create excessive glare in the vast majority of lamps, especially if the headlamps are aimed correctly. Which is never a waste of time to properly check and adjust.
>layperson is incapable of properly adjusting headlamp aim.
By this logic, most of the vehicles that roll off the lotnwith misaimed headlamps straight from the factory prove that
it's too complex a task even for the manufacturer! (New York Accent) The HoorrroooA!!!
Anyone who can find a remotely flat parking lot and a wall can check their headlamp aim and get it *pretty damn close*
>everything becomes out of spec when you put im the wrong bulb
Only arguably true if substituting a completely incompatible bulb type.
9011/HIR1 for the outdated 9005, and 9012/HIR2 for the outdated 9006 is not such an example.
In many instances, an H9 for an H11 is not such an example.
Etc etc