Has the internet and texting adversely affected young people's writing and grammatical skills?

Given the questions we see here, and especially the incorrect answers from people who obviously believe they are right, there has been a very significant drop in writing and grammar skills. The causes are less clear. Obviously, usage like u and ur has become common because of texting, but the simple ignorance must have a different cause. (Consider the person who asked this week whether "alot" or "allot" was the correct way to write "a lot.") That is more likely to be because of lower teaching standards, or dependence on spell checking.