Feel free to disagree.
However, those reading this should consider that the forces are applied to the steerer where the stem attaches. Also consider that bar widths and stem extensions are within known ranges that designers can factor when setting their design limits.

All this is not binary, and various factors can combine, so a long high angle stem will create a greater moment than a low angle short stem.

But in the end, designers have to factor the known variables, and set limits accordingly.

When friends ask me about what may be or may not be OK, I factor the variables, such as stem length, strength and riding style when making what will be a judgement call. Lacking specific details, I would suggest staying at least close to the guideline if not totally within it.

Those seeking a greater understanding should read up on cantilever structures because that's what the steerer/stem/bar assembly is.