We can say it's not us tossing the bottle overboard, but buying things the boats transport supports the system.
Among the most important leverage points for changing a system are its goals and values. Changing from growth to enjoying what we have and from externalizing costs to taking responsibility and stewarding takes time and is not the only course of action, but are necessary.
If we avoid straws and stop there, the action doesn't add up. If we use avoiding straws as practice then to avoid bigger things, then yet bigger things, I see avoiding straws like playing scales to learn piano. Scales alone seem like nothing, but they're how you get to Carnegie Hall.
In my case, starting avoiding packaged food led to no flying which led to leadership roles with my podcast, my second TEDx talk on environmental leadership this weekend (my first: http://joshuaspodek.com/my-tedx-talk-is-online-find-your-del...), and many people now contacting me that they're changing and enjoying the process and results.
Because jettisoning junk improves our lives, we expect to continue.
Only action -- not talking, not reading, not writing, not debating, not analyzing -- only action on one's values brings that joy. If straws are someone's starting point, I support them. Then I support them to continue. I believe everyone should start and accelerate as much as possible in changing their behavior and values.