The ultra-simplified answer to that question is yes.

However, how is it that replacing incandescent filament halogen or HID bulbs with their LED counterparts is increasingly common?

The National Highway Traffic Safety Administration (NHTSA) regulates automotive headlights performance through Federal Motor Vehicle Safety Standard FMVSS No.108, which concentrates on headlamps’ optics and limits the replaceable bulb’s type of lamp to incandescent halogen or high-intensity discharge (HID) bulbs, simply because that was the technology available at the time.
Automotive LED bulbs already existed for the May 2011 FMVSS No.108 amendment. Still, the American market was just starting to grasp the advantages of the new light-emitting diode technology.

It is also our hypothesis that the limited heat dissipation of the highest luminous technology of the time, HID, restricted FMVSS No.108 from allowing more illumination power from replaceable bulbs.
If LED bulbs existed at the time with their present cooling technology, we bet that authorized illumination levels would have been much higher.

During the last decade, the advancement in illumination power and reliability of automotive LED bulbs has been outstanding.
Its pace has been so swift that all the attempts to create halogen-to-LED replacement rules have been delayed.

Take, for example, the SAE Standard J3145, the engineering society’s project to regulate the matter. The standard creation task started in 2017 and is still a work in progress (WIP).

Formal questioning of NHTSA about the issue gets inconclusive answers that delegate LED compliance control to the states’ authorities.
Look at this NHTSA interpretation in response to an inquiry from an original equipment manufacturer, and draw your conclusions after reading the first paragraph of the discussion section.

And while all that is happening, the halogen to LED bulb “migration” keeps growing.

Couldn’t it simply be that LED headlight bulbs are safer?

How is it that DOT inspectors nationwide let commercial trucks freely ride our highways with “illegal” lights?

Would they let a vehicle transit if it is unsafe?

I don’t think so. They just know better.

The primary concern about powerful headlighting is the excessive glaring to oncoming traffic.
Better frontal vision can’t be enjoyed at the expense of the safety of other drivers.

Interstate commercial truckers ride 600 miles daily, mostly at night.
They are committed to safety. Their job requires that.
You can experience their sensitivity when you enter a highway and see them pulling their trucks over to the next lane to let you enter safely.
A non-professional driver probably wouldn’t do that.

If they are concerned about their poor headlight illumination, wouldn’t they also be worried about causing excessive glare to others?

After many years of trying to solve their illumination struggle, we have always witnessed that at FX-AA.
They want to see better but also wish for a pleasant night ride. And their night can’t be enjoyable if they keep annoying oncoming drivers with their lights.

Better illumination power must be provided according to the type of headlamp.
Our experience tells us you can’t put more than 3400 effective Lumen in a reflective low beam. Its scattered pattern with more light power will cause uncomforting glare.
However, projector-type headlamps can deal with more Lumens. Their narrow beam concentrates on a focal point. Besides, the projector lens offsets part of the power. There, you can go up to 5000L!

There is another reason worth mentioning for LED bulb adversity: They not only improve replaceable bulb OEM headlamps but also improve their performance at a meager cost.
If truckers can cheaply upgrade theirs with LED, would they need a new, more expensive LED-sealed one?

Therefore, sealed LED aftermarket headlamps are “trapped” by FMVSS No.108.
That is why their illumination is weak despite having multiple LED chips.
If FMSVSS No.108 “heat dissipation constraints” didn’t exist, they could illuminate considerably better than the replaceable-bulb type ones and, in that way, justify their cost.

One final word to signal the greatness of what the NHTSA official answered in the interpretation letter quoted above.
He literarily wrote: “While NHTSA regulates the manufacture and sale of light sources, it generally does not regulate the modifications individuals make to their own vehicles.”

What if the American regulatory system was so blinded to impede those modifications?

Evidence shows that LED headlights improve safety.
And, of course, LED bulbs must be regulated to avoid risky modifications, but in the meantime, let progress keep its pace.

There is no progress without freedom.
Under a static bureaucratic rule, even progress can become a crime.
Let us trust our “over the road” DOT officers. They know better.

Are automotive replaceable LED bulbs really illegal?