I know my grammar isn't perfect, and you are correct that I do need to check my own posts before posting, but what I normally do is just that. Sometime mistakes do slip past but usually I read each of my posts about 5 times to minimise the grammar and spelling mistakes.
I use Google Chrome which helps to keep most of the spelling correct and also for words I am unsure about I just google them.
One of the main reasons why I dislike bad grammar, is that I have Verbal Dyspraxia which effects coordination and speech. When I was younger nobody could understand what I said. I found that with better grammar in writing and also speaking helped other people to understand me, so I usually try and encourage people to use better grammar and spelling is to make it easier for other users to understand.
One of the other reasons I suggest good grammar and spelling is that translators like Google Translate have an easier time which means the post can be read by a greater community of people.
I was once on a forum that allowed a poster to get away with very bad grammar which resulted in about 50% of his posts were unreadable.
Also thank you for pointing out the grammar mistake in my first post, I can't believe I missed it.