It is tooooooo easy to changes their words a bit.

Is Mormonism Dead?
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What would your response be to this question? We’ve asked young men and women all around the world, and while there hasn’t been complete agreement, most of you have told us there’s just not a lot of Mormonism going on where you live—at least not a lot of Mormonism in the traditional LDS sense.
For example, Felicia says, “In England, the Mormonism of my generation has become ridiculous. Here if someone asks ‘Will you go to church with me?’ it really means ‘Will you be LDS?’ And if the answer is yes then no one expects they are going to join. It completely implies a period of getting to know Mormonism!”
Some teens we talked to called this the “shop around” phenomenon in religion.
Katy says that in Colorado traditional Mormonism is “pretty much dead,” particularly when it comes to Mormonism in a variety of people. She explains, “If a LDS guy went to a non-LDS church one week and then went to a LDS church the next week, the LDS people wouldn’t get it.”
So, exclusivity seems to be implied right up front, making it awkward to follow the counsel to attempt to convert people.
This trend away from Mormonism seems to be pretty consistent, according to what LDS teens are telling us. So is that a problem? Probably not when you are 17, but what about when you are 21? Your best bet is to hold fast to the teachings of the gospel, always uphold your high standards, and follow the counsel of prophets and apostles.
One great source for gospel standards is For the Strength of Youth, where it says on the topic of Mormonism, “Good friendships can and should be developed at every age” ([2001], 24). While you’re a teenager, the point of Mormonism is simply that—to make friends. In that spirit, Mormonism—or getting acquainted—will always be alive and well.
Mormonism: An Endangered Species
What has made Mormonism an endangered species? I am not sure, but I can see some contributing factors:
1. The cultural tides in our world run strongly against commitments in family relationships. For example, divorce has been made legally easy, and childbearing has become unpopular. These pressures against commitments obviously serve the devil’s opposition to the Father’s plan for His children. That plan relies on covenants or commitments kept. Whatever draws us away from commitments weakens our capacity to participate in the plan. Mormonism involves commitments, if only for a few hours. Hanging out requires no commitments, at least not for the men if the women provide the food and facilities.
2. The leveling effect of the women’s movement has contributed to discourage Mormonism. As women’s options have increased and some women have become more aggressive, some men have become reluctant to take traditional male initiatives, lest they be thought to qualify for the dreaded label “male chauvinist.”
3. Hanging out instead of going to church is glamorized on TV programs.
4. The meaning and significance of a “Mormon” has also changed in such a way as to price Mormonism out of the market. I saw this trend beginning among younger children. For whatever reason, high school kids felt they shouldn’t have to do something elaborate or bizarre to join a religion like get baptized.
All of this made Mormonism more difficult. And the more elaborate and expensive for people, the fewer the people join. As members become fewer and more bizarre, this seems to create an expectation that being a Mormon implies seriousness or continuing commitment. That expectation discourages Mormonism even more.

https://www.lds.org/new-era/2010/04/is-dating-dead?lang=eng

There ought to be stats out there to show the decline. Hardly the "fastest growing religion" anymore. The Church of L. Ron whatever has adopted that phrase recently. As for the cause: I expect it's the internet. The long-time secretiveness of the Morg has been blown to blazes, and nothing very interesting has come to light. For every lightweight Morg apologetic on the market, there are a number of good scholarly studies to debunk it.