When I type longer posts, I tend to use Microsoft Word to spellcheck. Also, I use dictionary.com often for individual words, as well.
However, I don't believe this guy is totally offbase, as many forums do have a spellcheck function. I don't think it's entirely necessary, but I wouldn't say it's a bad idea or anything. Perhaps not worth the amount of work it would be to insert, but nothing worth ridicule.
Being too lazy to correct your own mistakes regardless of a spellcheck feature, however, is.