The whole point of writing is communication. Improper spelling, grammar or punctuation makes it difficult or even impossible to understand.
The person doing the writing has the responsibility to be clear. Do not make the reader struggle to figure out "what you mean."
As a reader, it's not my job to figure out what you mean. It is your job to say it so clearly that you cannot be misunderstood.
Why correct or proper use of abbreviations and symbols important in writing?
2 answers
Why are VERBS important in sentences?
http://www.chompchomp.com/terms/verb.htm
http://www.chompchomp.com/terms/verb.htm