Thanks. I don’t know BApplication flags well, i will learn that. Multiprocess apps tends to fork() it may cause BApplication duplication.
Though I am not confident I read you correctly for my poor English skill, in my knowledge, it is not only for stability but also for security why multiprocess architecture is essential for current modern Web browsers.
Isolating content process (which parses and evaluates or executes unreliable input like malformed images, scripts or stylesheets hit known or unknows bugs) and privilaged process (accessing hardware directly or utilize powerful OS APIs) is to reduce risks when malicious code/contents succeeded to attack.
And isolating content proccesses for web site boundary is for protection safe site contents (like banking account infortdmation) from attackers malicious web sites.
As we use potentially memory unsafe code to layout and run web contents, so separate processes (implies not sharing whole memory) between them is effective to reduce attack surface from memory errors like bufeer overrun.