I have seen many poorly adjusted cantilever brakes, which probably explains why people think direct pull is "better". It's basically fairly hard to set up a V brake wrong - align the blocks with the rim, remove excess slack from the cable and you're done, more or less. Cantilevers need several parts set properly to work together, and the introduction of low profile arms didn't help in that respect. Traditional style arms, as used up to the 1980s like Mafac and Weinmann, weren't difficult - there was a fairly horizontal arm for the straddle wire attachment and a fairly vertical arm near the rim for brake block attachment, so hook it up and go.

Then came the low profile cantilevers - on these the lever arm is not horizontal and the brake block attachment is not near the rim, you need to set the extension of the blocks and the angle of the straddle wire to work together. It's not difficult, as long as the brazed-on bosses are in about the right place for the rim width, you just want to extend the brake blocks near the maximum and set the straddle so that, at the point the blocks hit the rim, the cable end is normal to each lever arm. You can tune it a bit either way (more powerful but softer feel or dragging, or crisper but less powerful) but that's the 1:1 "lever pressure to stopping force" arrangement.

The incorrectly set cantilevers usually have too much straddle height and not enough block extension, so the lever feels good but the blocks don't clamp the rim hard. Shimano tried to make it safer and more idiot-proof by using their single-sided link wire arrangement, complete with mark to show what the straddle angle should be, but that required the correct link length for a particular arrangement of braze-on bosses and rim width, and gave little scope for tuning.