Answer: Too many from a capitalist perspective? No. Too many from a usability perspective? Yes.
What do I mean? Working in such proximity to Silicon Valley, I have great opportunity to be impressed with all the technology and entrepreneurialism evolving around the digital marketing ecosystem. First, there were networks and search, and now there are social, mobile, application, exchange, data, location, and verification providers all looking to insert themselves in the online advertising value chain. If there wasn't a market for it, call it leakage or call it room for improvement, they would not exist. I have come to see it as yet another inevitable cycle of capitalism, creativity, technology, chaos, and eventual resolution within this still young medium.
From a broader market perspective, I welcome it because there is still great need to sort out the opportunities for maximized relevancy and effectiveness in digital marketing. Better user experience, higher supportable ad rates, and net more dollars moving to digital from other media or being earned by digital media as a precedent.
The challenge in the meantime, as a marketer or agency, is to identify and separate among all the players and new thinking what is worth adding to a plan and investing in. Additionally, because many of these technologies and approaches are so new, and potentially more grounded in technology or investment culture than marketing, they may not yet necessarily be compliant in word or spirit with the industry best practices as set forth by good groups like the IAB and the AAAA's.
How does it play out? The best of the new ideas eventually get distilled out, survive and flourish as key elements of digital marketing- whether independently or as part of a larger asset. Search did, networks did, social and mobile are and will. So, too, will the best of the application and behavioral data providers, exchanges and verification technologies.