u/Routine-Swan-1922

So I need to make a base for an 8x 12.5 Lifetime resin shed. I can barely afford the plastic shed, let alone a concrete slab. I am a terrible carpenter and am wondering why I couldn't use four treated 4x4x 8s on each of three sheets of plywood (plus one more for the extra bit) instead of making a complicated frame with joists 16" on center. I built something like this for my generator shed and it seems to be holding up ok. What am I missing?