Why is Projected Geometry locked?

I came across this post while researching the same problem with locked (fixed) projected geometry.
There wasn't much of an explanation of which sketches were causing the issue but I'm guessing it was the side panel that had holes projected from the bottom panel. In this case the issue seemed to be that the part itself was not adaptive, even though extrusion 4 was adaptive. The part had been adaptive in another assembly because I had to remove the adaptive flag in Document Settings.
I tested this by projecting a couple more holes and getting fixed sketches, after un-checking the flag and making the part adaptive any new projections were associative as expected.
I've also found that projecting anything to a shared sketch will cause it to be fixed.

I know it's an old thread but I ended up here searching similar things. With Inventor 2020, I found the projected geometry is Adaptive (yellow) when I select a face (projecting its face boundary) but goes fixed/locked and non-adaptive when selecting specific edges.

Also, for anyone interested, the concept of using adaptive geometry is a heated debate, just like "move face" in solidworks. All tools have a purpose and are included for a reason. To simply preach that it's terrible practice to use adaptive geometry is very poor advice. A better direction is explaining the causes of instability, risks and benefits. If you're designing one-off items and not archiving/reusing individual parts, there's nothing wrong with designing in a top-down scenario. You can also start top-down, then later fix those adaptive features and break the links. If you work in a production environment where parts are used repeatedly in multiple assemblies, then yes, you should always remove the adaptive links when the part is complete so someone doesn't accidentally change geometry that wasn't meant to be changed, or be left with broken references when the referenced parts are moved/renamed etc.

here are the files involved