Whoever thought it was acceptable to have a string of text that renders something unreadable or not immediately obvious to the human eye, was a complete moron.
I realize ASCII was limited, but one thing I like about it is I can understand every single character code, and program to handle all the edge cases with certainty.
The tags were needed for language indication to control CJK glyph variants. Flag emoji were grafted onto this scheme. The key is that tag sequences have to start with a valid introductory codepoint. Simple enough to strip out anything that isn't a flag.
I realize ASCII was limited, but one thing I like about it is I can understand every single character code, and program to handle all the edge cases with certainty.