The Risks sections are always like that. Any advertisements for stocks must have disclaimers about a wide range of possible risks, and that despite promising historical data you could lose your entire investment. Otherwise they could face expensive lawsuits when future shareholders claim that they were misled and not informed of these risks.
For example from Facebook's S-1: "Growth in use of Facebook through our mobile products, where we do not currently display ads, as a substitute for use on personal computers may negatively affect our revenue and financial results.", "We expect our rates of growth will decline in the future."
Google's S-1: "We expect our growth rates to decline and anticipate downward pressure on our operating margin in the future.", "We are susceptible to index spammers who could harm the integrity of our web search results.", "New technologies could block our ads, which would harm our business."
I cannot disagree with your attitude more. This company is saying they have an existing threat to their ongoing operations that _will_ be fatal, that they are unsure will ever be solved. This is fundamentally different than saying ad blockers could impact Google's business.
In a way, their honesty is unexceptional because they are required by law to be honest about their risks. But the level of risk is not usual.
Wide spread ad blocking would be fatal or nearly fatal to Google. The loss of the vast majority of their income and the resulting contraction that comes with that would probably tear apart the company.
This kind of language is very standard. The risks section pretty much always contains obvious platitudes ("An earthquake might destroy all our computers," "All our employees may quit").
The "risk factors" section is a required part of an S-1. The applicable SEC rule[1] says that the section should list "the most significant factors that make the offering speculative or risky."
You do see some really interesting ones from time to time. For example, RSA's annual reports used to include the following math-related risk factor:
"Our cryptographic systems depend in part on the application of certain mathematical principles. The security afforded by our encryption products is based on the assumption that the “factoring” of the composite of large prime numbers is difficult. If an “easy factoring method” were developed, then the security of our encryption products would be reduced or eliminated."[2]
I am by no means an expert here, and IANAL, but in my limited experience, yes it is very common to see statements like that in filings. They have to disclose any and all potential risks to investors, and as basic as it seems that is a risk.
I don't have much knowledge here, but I always thought one of the main reasons to go public because you want to raise money to either expand or you are strapped for money. If anything I would be suspect of companies who are extremely profitable and doesn't need to raise money at all but going public.
That number sounds correct. I've just been reading Pour Your Heart Into It (by the Starbucks CEO), which mentions "the SEC considers a company public if it has more than 500 registered shareholders", and that they had to request a special exemption from the SEC for their Bean Stock employee shares program.