I've got a slow connection on my Mac at home, and have consistently used Flash-blockers and ad-blockers over the years to control what's pushed to me. Even so, Firefox and Safari regularly stall and require a restart. May be my Mac, though.
The majority of OS X crash reports are due to crashing plugins. Java applets et al are so rare that Flash might as well be the only plugin that is used.
Whether or not your web browser crashes when it isn't using Flash is completely off-topic, unless you are trying to insinuate that Apple can't even tell from a stack dump where the crash originated. In which case, you're taking an awfully roundabout way to calling Apple incompetent liars.
Indeterminate. The logs show that Flash made a call. It didn't show where that call went when it failed. (I usually run Safari and Firefox in parallel on my Mac because both have stability problems, despite using a Flash blocker.) Most of the Player code is the same across OS, only the outer wrappers and connecting APIs differ.
On the happy side, there has recently been some increased cooperation with the Safari team, and when combined with the mobile optimizations you can expect to see some of the gains described by Kevin Lynch: http://blogs.adobe.com/conversations/2010/02/open_access_to_...
It is entirely unreasonable to assume that there is any statistically significant proportion of those plugin crashes that aren't Flash (well, maybe a few Java crashes...). Apple can't publicly blame Flash with any specificity, because they can't have Flash for OS X get abandoned until their mobile strategy has mostly killed Flash anyways. But they still have the raw data and stack traces. And that data indicates that Flash is by far the most crash-prone app on most Macs.