As a logic and math hobbyist, I'm wondering how you came to the following conclusions...

a) That they participate in an online community OR b) that speaking (in an offline community) would somehow help them to know how to spell the word

AND

c) That the word "hobbyist" comes up often in these communities

Thank you for taking interest in the spelling in my post. My autocorrect kept changing things and I must have failed to properly proofread. I do, in fact, know how to spell the word. As a human, I am prone to errors from time to time. I apologize for this.

Since grammar and language are your hobby, I would suggest you spend less time online, as correcting the rampant errors in language and grammar must consume a great deal of your time. I would also like to point out that there are many people online for whom English is a second language.

Words aren't real, we can spell them however we want. Don't be weird.