Not really, as even with "safe surfing" you can get hit by surf-by banner ad exploits. Reputable (heh) ad servers have been hacked in the past to feed end-users exploits.
Well then, you're adding a lot more security than just the browser. I don't get why pepole are messing with the hosts file though, and ad blocker is more effective and makes the hosts file superfluous anyway.
Why use a hostfile? If your request (to an ad site name such as www.doubleclick.com
or any big bannered ad server) is denied then you have just potenially saved yourself from a ad based background script drive by download and bandwidth to boot. Your typical ad blocker and/or proxy based ad blocker usually downloads the entire page then filters it according to whatever rules or actions that are programmed in it.
Bluetack B.I.S.S maintains a well monitored hostfile used by thousands of users (can't verify that without knowing their download counter) plus a lot of the users provide feedback on their hostfile.
Simply put, a hostfile cuts the request before it even goes out to the net. Proactive.
Yes, hostfiles can be poisoned/altered and all that nasty stuff but that would mean your machine already has other issues that need to be addressed.. the fact of the matter is, nothing is 100% safe aside from not going on the net period.
When everything is said and done, I would recommend using a hostfile from a reputable source. It's worked rather well for 10+ years
*knock on wood*
Critical surfing safely software: hostfile, ad muncher and a good antivirus program.. and by golly avoid those freebie screensavers/ringtones/games!