Try again. I checked the mechanics by reviewing Mizzteq and Mr Happy. Mizzteq never says you have to shield before hand and Mr Happy specifically states that the meteors do no damage if you have enough party members in them:
https://youtu.be/pZD7pOd4Gzg?si=lH7yTGaII5hXZE3J&t=905
To further this, the guide you linked can be interpreted as the heads doing damage, but I'm not here for vague wording, conveniently, there is also a video attached, a Ninja PoV as it happens. Go to Forsaken 1, the only buffs on the Ninja are Protect and Plenary Indulgence, the Path of Light hits and it does ZERO damage.
Here is that point in the video, starting at the point just before their HP reduces to 1.
In this case, I do believe I have provided enough evidence to say, without a doubt, The Path of Light does ZERO damage.
If you don't want to provide explanations as to why your other videos are not classed as DDR, I am just going to ignore them. Evidence without explanation is not evidence at all.
The problem is, you are clearly looking at things from the point of view of a static group, where players know what they are doing. However, these things also need to work in a random group setting and being unable to attack because your TP regener didn't regen your TP, or you just did not get randomly matched with one, was a problem. This is only made worse by the fact random groups are, by their nature, going to do less damage than a static group, so fights take longer, which gives more chance for this to happen.