It could have been that, when the inbound went tech, they planned to use another a/c for the return but might have been unable to get standby crew in time or a host of other things. Depending on the route, if they have more rotations later in the day, they would plan to txfer pax to that/those. This is standard for any company.
If they told you that the flight was canx and then COULD operate it - what would have been your reaction? I am not saying they did it well but they appear (by your report) to have done what most would expect.
As an example, I have a long haul booked and discovered by chance that the departure time had gone forward by 95 minutes. It took the carrier another ten days to telephone me. I asked them why they could not have sent me an email (I am FF with them) and they could not answer it. Since that is a main line carrier and I am in a premium cabin and it has trashed my onward connection, you could say that I am not pleased. But I don't try and spread bad stories on the web about every little thing that goes wrong in my life.