your tax preparer was incorrect. "Hobby" income is reported and the costs applicable to earning the income is deductible. Now it might change where the income and expese is reported on the return and might be subject to limitations (which might be what your preparer was telling you in simpler terms).
There have been several preparers in just our state who were subject to jail time for falsifying returns and one favorite was hobby income and expenses. It was the people who went to them that really got hurt. I know as I audited hundreds of them over several years. Very few people actually make a significant profit from their hobby. I knew a longarmer who spent probably tens of thousands on supplies (she had over 7000 computer patterns, hundreds of spools of thread, bolts and bolts of batting and lining, etc. Not to mention the $30,000+ Statler Stitcher). She could not support herself doing quilting and got so tired of all the work so she sold the whole thing.
She said she paid off the machine but when all was said and done she had no taxable income from the business.