I had not only bottles but - gasp! - samples of formula in the house (US hospital, they were shoving it as us, we took the 'free diaper bag' and it was full of wee bottles of formula). DS had some of that formula, in the first week, when we hadn't got his Tongue Tie figured out and he was getting dehydrated. In the end I've EBF from day 8 for 7 months so far, and there's no signs of stopping.
I think that establishing breastfeeding can be really bloody hard work (even if just the hard work of "now I must sit here and not do anything else and feed this baby for 45 minutes, after which he will sleep for 20, and then wake and want to feed again. And I must not go crazy. And I can't reach the remote.") So for some people having the bottles/formula right there can be too much temptation, like having cake right there can hurt your diet.
I was very bloody-minded and determined to breastfeed and I could afford to call in a lactation consultant when, in my particular circumstance, it went tits up (hah! Sorry). Therefore it worked despite the bottles and the formula. I don't think having the bottles in the house will hurt your chances, exactly, but I imagine the thinking behind 'don't do it' is simply that there's no way having bottles around will HELP you breastfeed. In the way that, say, someone else doing your housework and some dvds will help you breastfeed. (thanks mum!)
The nice nurse who got us started in the hospital said "Every breastfeed counts. Just do it as long as you want, because every one counts, and then there's no pressure." It got so much easier for me after the initial 6 days of "oh god why isn't he getting milk" and then the initial 8 weeks of him feeding NON STOP... but at first, it's hard. Taking the pressure off helped. I found myself thinking 'well I could stop tomorrow, I've done really well to get this far. I'll just feed him tonight and decide in the morning' - and then each morning thinking 'aah, ok, I'll keep going, he's so cute when he's face-in-boob...'
So now I'm determined to get to a year because that's when the health benefits for ME kick in, and I feel like I should get something out of this! Plus, bfing has been downright EASY since about the fourth month, so when I thought "oh I could stop now" at six months, I couldn't face the faff of formula.
Erm. I rambled, sorry! I think if you can find your balance point between being determined enough to push past the frustrating parts, and cutting yourself slack if you've actually had it and you'd like to stop, you'll do fine. Every drop does your baby good, and if you decide to stop, congratulate yourself for every drop that your LO's had. :)