Why so spell checkers suck?

Why do so many forums and or application forms have spell checkers that don't recognize the correct spelling of many words? It really grinds my gears. For example the word "pedophilic". According to various dictionary sites that is a correct spelling. Is it adjectives that these spell checkers miss. What's weird is this site as I was typing it had the red squiggly underline as I spelled "pedophilic", but then went away. I was using this word to describe a female commander shepard on a mass effect face site. It looked really young. But anyway there have been other words I can't remember that I've seen this. It's really annoying cause then you're thinking wait did I spell that wrong?

Spell checkers arent perfect unfortunately.... Of course this is why they have the "Add Word" button. End of the day, you shouldn't be relying solely on a spellchecker anyway because of course you can spell words incorrectly but if they are actual words then it won't flag them.

Example:
Eye halve a spelling chequer
It came with my pea sea
It plainly marques four my revue
Miss steaks eye kin knot sea.
Eye strike a key and type a word
And weight four it two say
Weather eye am wrong oar write
It shows me strait a weigh.
As soon as a mist ache is maid
It nose bee fore two long
And eye can put the error rite
Its rare lea ever wrong.
Eye have run this poem threw it
I am shore your pleased two no
Its letter perfect awl the weigh
My chequer tolled me sew.

To avoid having misspelled words I have...Dictionary - Wikipedia, the free encyclopedia
bookmarked.
That way I know my replies or post are clear and concise! IMO

metalmania31 said:

I always double check I'm just ranting about spell checkers saying a word is incorrectly spelled when it is correct.

I understand what you are saying and the frustration that goes with it.
I just deal with it and let it go.

Just type in ok and see what happens!

Just think, people used to not have to deal with troublesome spell-checkers

People from Australia, New Zealand and Great Britain spell a lot of words differently to the USA and can cause confusion as to what spell checker to use.