Plate perpendicular to bottom of square brick/plate: is this connection legal?

This is closely related to the question about jamming plates underneath 2x2 round bricks, (and indeed prompted by a comment there), with differences explained later.

It is possible to attach a plate (or tile) to the underside of a square rectangular brick/plate/tile, between the wall and the tubes, like so:

Note how the distance between a brick's wall and its inner tube seems to be the same as the thickness of a plate:

A few observations:

• This connection feels looser (seems to have less clutch) than using a round brick.

• For 1-stud-wide plates, this connection doesn't guarantee a straight angle. The edge of the plate sits loose inside the brick.

• For post-2005 regular bricks (i.e. non-sloped), since they have thinned walls with notches at every stud, the connection is particularly flimsy. A 1-stud-wide plate just won't get any grip at all.

• The walls of rectangular bricks are connected to each other, so bending a wall "outwards" (to jam a plate/tile inside) means bending or stressing the perpendicular walls (as far as I understand the physics of solid materials).

So:

• Is this connection "legal"? (i.e.: Does this connection stress the parts involved?)

• Has this type of connection been used in any official sets?

• I'm guessing the "thinned walls" comment is the key indication that Lego doesn't consider it legal - otherwise they'd have had to preserve the old style of wall. Commented Aug 6, 2022 at 14:47
• Would this connection be considered "in system"? it seems the parts are offset by half a plate in two dimensions, and half a stud in the other, which would be in system. Commented Aug 7, 2022 at 23:15
• Indeed - the offset is 4 LDUs (half a plate) in two axes. The plate, however, can slide along the third axis. This becomes obvious when using a 2x8 brick: a plate/tile can slide between the wall and the tubes. Commented Aug 7, 2022 at 23:25