I think it would be helpful to be able to still chat while turning off Allied Chat in the options.

I feel this way mostly because while I may not want to always read what my allies are saying (largely the flame or chatter unrelated to the match at hand, which happens enough to be a problem for me), I'd still like to be able to send strategically relevant messages (like what should be done, or we should consider trying in a given moment). Right now (unless this was changed in the last day) it simply restricts you from sending anything if you have the option to turn off Allied Chat selected in the options menu.

The potential of people muting their allies and proceeding to say things that might anger allies (not enough to breach ToS, but enough to stir up trouble/instigate allies into saying things that might actually breach ToS) while not having to see any replies/reactions in chat is at least one potential "risk", yes. But I think it's worth that sort of risk in order to be able to convey helpful information, without being forced to see things in chat yourself that don't contribute to winning the match, and in some cases might put you on tilt (depending on the person, the day, the circumstances, what was said, or your current mood before the tilting thing happened/was said, etc.).

It's similar to how I'd like to be able to still ping, in spite of muting one person who is being annoying with their pings.. or perhaps on much rarer occasions a whole team of people using their pings in ways that are not helpful towards winning, whether directed at me or some other player/s.

[Edit: just to be clear, I know we can still ping under those circumstances, but it's a decent comparison I think if it were not possible to ping after muting your team's pings. Disabling your team's ability to be "toxic" (in terms of at least what you see, even if the rest of your team still sees it) or whatever else that isn't helpful towards winning, I feel should not disable under any circumstances that I'm aware of presently, your ability to convey (hopefully) helpful information that could lead to a win.]