There is a difference between distorting an existing icon and designing your own icon from scratch and deciding that the distortion is part of the design. Google is warning you against the former, but no-one can or should stop you from doing the latter.
Lots, if not all, style guides of brands and logos prohibit the distortion of an icon or logo. Rightfully so, because the designer has been thinking about and tinkering with the icon or logo's proportions and other attributes. It might be a good rule of thumb to never distort a logo or icon you did not design yourself.
If you are designing your own logo or icon from scratch, nothing prevent you from taking the decision the logo should be in perspective, bloated, fisheyed, skewed, or distorted in any way. That is up to you, the designer. When this is a good idea is, in my opinion, an opinion-based question.