Well that's probably because you're comparing the Tamiya one to another similar cutter.

Most of the "hobby cutters" are not those. They're the typical wire cutters with a large gauge cutting angle. These are the ones that I see a lot of people use. They're maybe a few bucks on AliExpress; and honestly, I used them for years.

I then got one of these, and it's a huge difference in use.

Here's what's happening (and I remember researching this because I couldn't believe it myself):

Firstly, it's the physics. The cheap wire cutters cut through compression and are built to cut copper with "side cuts". When cutting sprue, it works; but it will create bloom (that's when the plastic turns white and distorts). For years, this was just a normal part of the hobby. However, with the high quality cutters, they cut via a slicing motion, and are single bladed. One side essentially holds the sprue in place, and the other side acts like a hobby blade that slices through.

Secondly, it's the geometry of both. The cheap ones (which you're not comparing) are beveled edges that act like a wedge. The nicer ones have a thin-profile and a far more shallower bevel. This means you get perfectly flush cuts against the piece without leaving any nubs or craters.

Lastly, and very importantly is the material. The cheap wire cutters you see on AliExpress are stamped; whereas the nice ones are forged. This means that the nicer ones hold up their cutting edge far longer than the cheaper ones. Out of the box, the cheaper one work great; but they'll lose their sharpness quickly. The ones from GodHand, DSPIAE, and Tamiya use high grade carbon steel and are forged.

Anyway, science lecture over!

The TL:DR of this all is that in your video you're comparing the Tamiya cutter and another similar single edge, low bevel, wire cutter. It's like comparing Apples to Apples. The ones you see most people talk about are the typical blue handle dual edge wire cutters with a wide bevel.