Just because you can use them doesn’t mean you should.
When posting here, the idea is to convey your message in a manner that others will receive the message you intend for them to receive.
Anything that interferes with that is not good.
Things such as:
Excessive emojis
lack of paragraphs
bad spelling and grammar
use of uncommon abbreviations that most others would not know
use of “leet speak” or other slang
These types of things obscure your message and should be avoided if you want your message to be received well.