I would think that is true, as a general trend, and I believe many of the ex-members who say they never would have gotten involved in Scientology had the Internet been around. But come on, wouldn't it be nice to have a one-stop-shop for all the answers -- things you can't find on the Internet, like a cure for cancer or the group that is responsible for all the bad things in the world? (A. Engram removal B. Evil Psychs)
However, Scientology has a lot of money and reach they didn't have in the '60s, and they can reach out, sometimes through their front groups, to people who are more vulnerable to it, particularly in the 3rd world. As long as involvement by these people remains stable, and can be used to milk millions out of whales like Doogie -- although he is pretty singular as their top donor -- it can limp along for quite a while.
I do not think beliefs in astrology, aliens among us, reincarnation, ghosts, etc. are dead in young people just because they have the Internet, and there are some people who are overwhelmed by the amount of information on the Web and they seek to guided in a more structured environment where they are loved bombed coming in, and then feel like they belong to an exclusive group. I think for some of them, they are very excited by the idea of belonging to a group that is going to transform society, end drug use, stop war, and save the planet, as well as unleash potential within themselves to be something great.
I just read a bio of Kim Philby, who worked for MI5, but fairly early on in his career with British intelligence secretly worked for the KGB and finally defected in 1963. One of his motivating factors to work for MI5 and then defect to a the Soviet Union was to belong to a group that was exclusive. Scientologists feel this, especially the ones working on "operations" or for the OSA. Of course when he ended up living in Russia, he found out that in practice, Communism wasn't all it was cracked up to be.
Even decades before the Internet, the cost of Scientology was a huge red flag for me. But there are people who still want to pay for things, because they feel that it must be real if it is so expensive; you get what you pay for.
One thing I find the Internet spectacularly good for is consumer research and comparison shopping. I can't help but think eventually everyone will want to understand what they are getting for their money in a pay-to-play religious scam like Scientology. And how could they possibly get involved without at least reading the Wiki on Hubbard and Scientology. I don't know, maybe it's for people who like a mystery, risk and adventure.