One commonality among all of them is being marketed as a service for smaller-scale companies while having the double-edged sword on the backend that is most likely what they are really after

EDIT: smaller scale companies and individuals

Although not quoting until now (my mistake), my reply was specifically in response to your previous point:

I don't think that's a reasonable comparison [...] it doesn't give insight into competitors metrics unless those competitors choose to share that information

The lines begin to blur especially when discussing means of accessing the internet (especially most efficiently/safely) and/or core (semi-artificially-required) mobile phone operating system components!

If nothing else they offer the path of least resistance. Any best-of-breed solution (GMail, Google Docs, Chrome - all somehwat a matter of opinion) or de facto monopoly-ish position (search, free analytics, Google Play Services?) by Google offers the potential for them to gain info on competitors in much the same way Amazon can take over succesful verticals originally occupied by a third party.