No, notice that "builtins" was in quotes. web2py does not actually add new members to __builtins__. Rather, web2py executes model files, controllers, and views in a pre-defined environment that includes a number of web2py API objects (though not the entire API). This includes about a dozen core objects, such as request, response, session, and cache, plus a set of HTML helpers (all derived from the same class and named after their HTML counterparts) and a set of form validators (all derived from the same class). This is all very well documented.
People like you who have never actually used web2py routinely express concern that this will somehow set up false expectations and confuse people about how Python modules and imports work, but in practice this is simply not the case. Note, web2py also includes a number of modules that require explicit importing, and applications can include their own modules as well as import standard library and third-party modules. As a result, web2py developers are perfectly comfortable with normal Python imports and do not have any false expectations.
Web2py is indeed using its "great power" responsibly.
People like you who have never actually used web2py routinely express concern that this will somehow set up false expectations and confuse people about how Python modules and imports work, but in practice this is simply not the case. Note, web2py also includes a number of modules that require explicit importing, and applications can include their own modules as well as import standard library and third-party modules. As a result, web2py developers are perfectly comfortable with normal Python imports and do not have any false expectations.
Web2py is indeed using its "great power" responsibly.