Availability of information is a key thing that has changed. Consider how you'd get information without the internet? You'd be looking at company reports (on paper of course), listening to what your broker said, and then there's the media.
So whilst it was possible to get info on one particular company, there's no chance you were going to do any sort of comparison of every stock on the ASX. Even just comparing the top 20 would be a monumental task when you've got to get all the information from various sources and put it into some form that enables comparison. That leaves you at the mercy of broker recommendations and the media.
End result = stick to large cap "household name" stocks unless you're really, really keen on spending a lot of time on research and/or have a lot of trust in what your broker is recommending.
But that said, if you wanted to make money in the second half of the 1990's then it was pretty easy. Just put your money in an "all stocks" managed fund and watch it grow. That's it. If managed funds are routinely returning 20% per annum then it's hard
not to make money.
It all worked so well until quite a few people found out the hard way that a certain well known, high performing fund manager of that era popular with the masses had put pretty much everything into dot.com stocks. It worked fine until suddenly it didn't.....