This raises an interesting comparison. Bypass v. Magnet.
Magnet should catch undissolved ferrous debris of a certain size range (?u) and above that comes near enough to the magnet.
A bypass filter should catch ALL debris, 2-3um and larger IF the lubricant passes through the filter. Again, does this make sense for the average passenger car owned 6-8 years? Probably not.
Magnets are cool and great and - yes I am opposed to some lousy magnet that loses flux at 250°F stuck in a filter center tube and may heaven forbid move (yes these are sold!), or a weak magnet on the outside of a steel can (yes these are sold as well) - but otherwise yes, I like GOOD magnets! Especially in a new engine.