this has gotten beyond silly.
many thanks to those who have defended me.
for anyone not involved in the spat still reading, let me try to clarify why this matters without forcing anyone to reply with another inflammatory post. i'll have to let FW's childish taunts slide without reply in order to stick with my pledge. if i don't, this will go on forever.
anyway, for those who read this thread to gain knowledge rather than to watch or participate in the spat, here is the issue:
if you are someone in your early 20s with minimal funds to either save or invest, you commonly hear advice to set up an emergency fund first, and only after that savings is in place should you invest for your retirement. the OP seemed to be in this situation due to his lack of knowledge of IRAs and mutual funds.
the question of whether or not you can withdraw contributions from a Roth IRA penalty-free is extraordinarily relevant to my hypothetical fledgling investor. if you cannot withdraw penalty-free, then you should not risk your short-term financial well-being by tying up all of your savings in retirement accounts.
however, if you can withdraw contributions penalty-free, then you can take advantage of tax-preferenced retirement savings while having the peace of mind that the money is available to you penalty-free in an emergency. in other words, you can have your cake and eat it too. my hypothetical early 20s individual should definitely open a Roth IRA. hopefully no emergency ever arises and s/he will be able to leave that money in the Roth IRA until retirement. but the fact that s/he can withdraw that money penalty-free (the contribution(s)) means that s/he does not need to first build up emergency savings.
this is a substantial benefit that should not be understated. i didn't know this in my early 20s. if i had, i would have created a Roth IRA much earlier. and that's why i think this point is far more than a minor one. all of you out there in your early 20s with meager savings accounts, this knowledge should allow you to open a Roth IRA with little fear. and if the choice is between not opening a Roth IRA or opening one knowing that you might take some of the contributions back in the future out of necessity, the latter is clearly better.
of course you never want to withdraw money from retirement accounts, with penalty or without, unless there is a very good reason. and if you follow my advice and invest in a Roth IRA without first having some emergency savings, please make sure that you invest in low-risk vehicles (e.g. money market funds) until you do have some emergency savings somewhere else.