If they're going twice your speed, they can go twice as far. Assuming they're personally providing at least half the power over the course of the bike ride, they're expending identical calories to you, possibly more to compensate for their heavier bike.

It's true that the moment-to-moment intensity is lower, but lowering intensity is some of the most common advice given to people struggling to get into a sport without their body rebelling, and the challenge as often as not is that they're bored at the beginner's pace and want to push more.

It's the same concept as assisted pull ups or knee pushups. Sure, you can build up from scratch by just doing a fraction of the duration, but that's boring and frustrating. Being able to actually move your body the full distance with less effort is a much more engaging way to build up the physical capacity you need to do it without the assist.

I'm sure it depends on geography. In my area, the e-bikes are pretty much confined to the rail-trails, which are flat. When I get out into the hills, the bikes buzzing by me at twice my speed are all conventional. I've seen no e-bikes out there.

Also, making educated guesses, it may be a non-issue. Most of the e-cyclists in my area seem to be divided into two categories: 1) What I would call adult beginners, who had bikes but didn't ride them much before they got e-bikes. 2) Practical uses such as commuting, transporting kids, etc. And recreational use of e-bikes seems to have peaked while basic transportation use continues to grow.

The commuters pass me at a high speed, but they're also in good control, and polite. The beginners tend to ride at the same speed as conventional bikes, or even slower.

The real problem that e-bikes solve is not faster horses, but whether someone wants to get around on a bike at all.

I think the key factor is amount of rides. On a one to one comparison, obviously an ebike is less work but how much more often are ebike riders riding?

I don't own one but there have been plenty of times in my life where I go somewhere ina car that's in biking distance but don't because maybe there's a decent hill on the way and I don't want to arrive sweaty.

The easy ride an ebike offers opens up more opportunities to ride.

On a particular climb, sure: energy is conserved, but this is a curb-cut effect. It's easier to make a little jaunt on an ebike, so people are more likely to use their ebikes to take that little jaunt.

More rides, for more distance. The integrated effect is more energy expended.