With the exception of social media professionals and academic journalists, the majority of what is written by the general public on social media is not edited, supervised or checked to ensure that proper use of the English language is taken into consideration.
That being said, the number of typos and mistakes might lead to undesireble reactions, not all necessarily negative. One of the most notable ways that social media has influenced the English language is through the appropriation of existing vocabulary. Words that had existing meanings, have now been given other meanings in an online context, which then spills over into verbal communication.
Typo vs. Mispelling
A typographical error (often shortened to typo) is a mistake made in, originally, the manual type-setting (typography) of printed material, or more recently, the typing process. The term includes errors due to mechanical failure or slips of the hand or finger, but usually excludes spelling errors.