On a cold start-up (cold air, water, oil) the bypass is what prevents the filter from being blown right off the engine. If it doesn't, the next weakest link is probably the core plugs for the oil galleries. The pump relief valve is far too small to handle the excess pressure.
If you do this, I suggest 5W20 or a multi-grade with a very low "winter" viscosity.
To insure all the oil is filtered, you need a really big filter or 2 in parallel.