Nice article, but the reason for the oscillation between de-centralized and centralized, public domain and corporation-owned systems is not because of innovation.
It's because private businesses at first invest and try to grow the user base, for the ultimate goal of consolidating the market into a pseudo-monopoly. Once that happens, then monetization starts in full steam, and the corporations try to extract as much revenue out of this situation as possible.
This is obviously painful for the users, because they are now forced to carry the weight of the profits extracted off of the business. The value provided by the service is counterbalanced very precisely by the revenue extracted from the user. The hypothetical pain of moving to an alternative platform is also taken into account. Using the system becomes zero-value or even net negative for the user in the median case.
The users start to evaporate at this point for obvious reasons. They will move to an alternative de-centralized, free and public domain utility, or lacking that, to some small scale start-up provided utility which is still in an investment phase, which provides roughly, if not perfectly for the same need.
The cycle continues until the need is provided by non-commercial and de-centralized systems, and no business sees a viable chance of gaining an exploitative pseudo-monopoly on it.