yes it's bad if you put too much pressure on them, show your disappointment if they don't succeed, in the past some parents were even abusive to children who had an accident.. It was a good thing when drs started saying, look, if your kid is not PT, it may be that they are not ready.
However, the disposable diaper companies have really jumped on the bandwagon trying to tell us that ALL kids are better off in diapers till around the age of 3 or 4. Pleeeez.
IMO it's not bad to introduce the potty in a fun and sensitive way, at any age. Keeping in mind that most kids will not be PT overnight nor will they be able to get themselves to the potty in time every time--parents have to help in the beginning! And possibly for the first 6 months or more.
By advocating "child led PT" disposable diaper companies try to keep kids in diapers longer... therefore making more money. IME very few kids end up doing true child led PT at any age, though the unsuspecting parents are always waiting for that to happen... until finally it does not happen and their child has reached an age where the parents start to get nervous they will never PT... and then they end up doing parent led PT anyway.