I should perhaps have said that my tanks had been set up for over three months before I added fish, giving plenty of time for the plants to become established and spread. I do believe that a more complex ecosystem is more stable and so having a variety of plants, algae, no doubt many different bacteria, and even snails, is a better environment for fish. I did cycle with ammonia, though by squirting some in every few days rather than the careful measuring and testing. The only time I used the measuring method was to test before adding the fish. And of course I made large water changes just before adding the fish, but my subsequent changes have never exceeded 10% at a time.
There's a bit of a myth, I think, that having things like thread algae and snails in a tank, is somehow a sign of poor water quality, while crystal clear water and algae-free glass indicate a healthy tank, but there are many examples on here of people who have apparently "pristine" water conditions yet have still lost many fish. One reason I wanted to avoid adding fish little by little is that it seems by far the major source of disease is newly introduced fish. By adding all of my fish at once, at a time when I knew I would be able to keep a close eye on them, I was able to look out for signs of disease and be ready to treat if necessary. Once you have a disease-free tank, the chances of an outbreak are much lower if you don't add any more fish.