Hmmm. Not certain I agree with that Malcolm. Evolution can happen through simple mutation. Now you may argue mutation only happens when needed but simple exposure to radiation can trigger mutation which may result in a change. But that doesnt mean the change happened because it was needed.
If there is an unexploited niche, life, if available, will evolve to fill it. It could be through stray radiation modifying DNA, it could be dumb luck. In a reasonably stable system, change is rarely needed, but can happen anyway. The basic design of sharks has remained pretty constant for many millions of years, but there are variations.
Life would find this similar to our rotating planet where it's hot on the equator while the poles are freezing.
The presence of a narrow strip that is neither hot enough to melt metal nor so cold that even a Geordie would put a coat on, with neither night nor day nor seasons, would probably not be good for development. There may be life there, but to quote Spock, "...not as we know it". It would probably be much like Venus - an acid atmosphere and not tectonic movement.
We have the benefit of a huge satellite which acts as a stabiliser, keeping our tilt fairly constant and giving us seasons. It also provides tides, which are the marginal conditions needed for setting up the original evolution mechanism. It also probably helps keep the core temperature high enough so that our water doesn't just drain away and stay there.
We have had several happenings that have shaped life on this planet - the original thud when we gained the moon, then about 259 million years ago when "something" happened to wipe out most of what had evolved, then 65 million years ago when the slate was given a good wipe again. Just how much of this was essential to our development is really impossible to say, but is we needed all of it, any other planet might well need something similar, and on a similar timescale to arrive at a compatible point.
Being the right sort of size and at the right distance is not the entire story. There might be millions of such out there, but if it also, for each one, needs a few several million to one chances for life to establish and evolve, there really aren't going to be many.
"Our findings offer a very compelling case for a potentially habitable planet ... The fact that we were able to detect this planet so quickly and so nearby tells us that planets like this must be really common."
I would read this as a coded way of saying "Keep the funding coming, I like having an indoors job with no heavy lifting". Is that cynical or sceptical?