Indeed - no "stack"...
yet - unless google starts "integrating" the services into each other (integrate - not just share a home page as a starting point).
The stack example, indeed, seems misleading here.
On the other hand - while you defend google here - think back to some of the issues in the MS anti-trust case:
- MS used proceeds from other areas to funnel huge amounts of money into IE development - much more, than any start-up could hope to match.
- By including IE into Windows, for many people (normal users, not people working in IT) they eliminated the need to even look for other browsers - no matter, whether other browsers might have been better.
- The inclusion of IE also meant the end for commercial browser makers - as they wouldn't have an alternative source of income. "Netscape" failed, their browser ultimately only growing because it was completely freed and open-sourced: In effect, MS might still channel more money into IE; but against the open source community that would not necessarily help, as the open-source author doesn't need to "show quarterly numbers"; quarterly profit reports, etc -- as long as the open source developer gets an income (which in many cases may stem from an unrelated day-job)...
In google's case, there is no full integration of services - but:
- income from the advertising (which the search engine generates / facilitates) supports an ecosystem of other software - a free calendar or documents - services that _depend_ on their ad business generating the income for them. Same as MS Office paying the bills for IE.
- the same landing page (www.google.com) being a straight entry point to not just the search, but other free offerings unrelated to search (like the news, play, ...) gives those extra services a big head-start over their competition - and one they can't hope to match (no ad space sold on the landing page).
These things make it more difficult for new enterprises to form - and it's reasonable to expect that any new area popping up on the web, google will not just also try to profit from (which would be fair enough), but they can (easily ab)use their position to help their apps further by giving them privileged exposure on their search page and continue to fund them for extended periods of time to prevent other entrants getting into that area.