Outrageous bargain for a Canon EFS telephoto

We have plenty of great bodies and L glass for our business, and a 5D Mark IV with something like the 70-200 f2.8 IS L II, say, will still provide some of the best image quality available. But for travel, we love our EFS STM lenses on cheaper bodies.

No, they don't offer L quality optics. They certainly aren't built anywhere close to L standards. And they're pretty dark (max aperture) by comparison. But those things aren't the point.

The EFS (and STM versions, subsequently and specifically) are designed for amateur and enthusiast level use, to be sure. But they still offer quite good image quality, thanks to modern computer optical design technology, and incredible speed with the right camera. They are very quiet to operate, too, and even feature built in stabilization. But where they excel is in putting all of this into a package just a fraction of the size of comparable full-frame glass. It's incredible to realize that the 55-250 STM offers a comparable/similar focal length (on an APS-C sensor) as large and heavy Canon's 100-400... and that's even with comparable f-stops! That the 55-250 can be bought in new/refurb direct from Canon for just over $100 can really cause someone to question the virtue of, say, an 80D with 55-250 costing $1200 or so versus a 5DIII with a 100-400 costing FOUR TIMES that.

Obviously, there are plenty of other differences between the two hypothetical kits just mentioned, but I do believe that the comparison is warranted for the amateur/enthusiast who primarily shoots outdoors at these focal lengths and equivalents.