Not during the first 12 days, but after that they do.
What whoever told you that might mean is if you use potting soil w/chem nutrients already in it, adding more would hurt.
The best potting soils have a mixture of compost & peat moss, with seabird/bat guano, seaweed/kelp, worm castings and a bit of hydrated lime, and perlite.
Some growers like to add lots of perlite but you should never use more than 15 % imo.
A soil with these organic nutrients doesn't need any add'l nutrients for the first 4 weeks or so. Then it's time to add small amt's of nutrients to the water when you water the plants.
For a beginner, I'd recommend Fox Farms nutrients. You'll need 1 kind for veg and another kind for flowering.
Top quality potting soil is expensive (Fox Farms Ocean And Forest and Black Gold Potting Soil start at $10.00/bag) but is very cost effective. Your plants will grow faster, be healthier, and you'll have more buds to harvest.
plants need different nutrient levels at different stages of growth....check out some manufacturers websites and look at the NPK ratios for comparison....they'll help give you an idea of what nutes are needed in the veg stage and what nutes are needed in the flowering stage....
A vegging plant needs lots of N (Nitrogen) and magnesium, while flowering plants require lots of P(phosphorus). If you take Ganja's advice and go with a quality nute like Fox farms, then you will not have to really worry about this as your veg formula will be formulated for veggin and your flowering nutes will be formulated for flowering.