Two things
1) EIC is not a business-related issue. It applies whether you are an employee or self-employed. Has nothing to do with business expenses / write offs. You can't base a business plan around having children under 18 or not.
2) I am guessing elsewhere's original line of thought was if you have enough expenses, you don't make a profit, so you don't get taxed. That is directionally correct, but substantially not true. Plus, to pay for the EIC, the government came up with the AMT - Alternative Minimum Tax, which prevents anyone making over a certain amount from minimizing their tax liability down to 0. You can have all the legitimate deductions in your business that you want, in an effort to reduce your personal tax burden, but ultimately the Gov't says "you make too much money to pay no tax", and you get walloped, rendering all those "write offs" as useless.