I’ve seen a lot of linguists and such folks saying that the move towards mostly writing now on electronic media, with the accompanying prevalence of spell-check and auto-correct, is probably at least partially to blame. Before, if you didn’t know for certain how to spell a word, you’d actively go look it up in a dictionary; when you were done writing, you’d go back and proofread to make sure that you didn’t spell “tomorrow” as “tommorow” or whatever. And schools would focus on memorising correct spellings. Now things usually work differently: if you don’t know how to spell a word, you just type something that you think is close to correct, and then the computer will give you a list of suggested proper spellings to choose from (or even just choose one itself and replace your own weirdly-spelled word automatically). People get used to that, and when they are typing on programs that don’t include such correcting software they still type in the same way. Meaning that they’ll just type whatever sounds close, and then subconsciously expect the computer to fix it for them if it is wrong. They don’t look back at what they wrote, they don’t check the spelling themselves, and they don’t self-correct any bad spelling habits they may have acquired.