The thing many novices don't realize is that spokes primarily hold the rim in place in relation to the hub. They don't have the capability to change the rim itself. If the rim is physically bent no amount of "truing" will fix that problem. If you "true" by tensioning the spokes evenly the bend will remain exactly the same. If instead you try to make the rim run straight regardless of tension you will end up with very uneven spoke tension and an out of round wheel (because the spokes pull in more than they pull to the side).

Nothing wrong with using a tension meter, but it's a final step, not a wheel building tool, and in my opinion it detracts from one's ability to observe and think about the dynamics of a wheel. It's somewhat analogous to what happens when people slavishly follow their GPS off a pier or into a brick wall (yes, both have happened).