Definitely not.
Most ISP's that provide Usenet access only provide access to a limited number of newsgroups. This is because they don't want to have anything to do with all the warez or porn groups. Also, if they offered access to the large multi-part binaries groups then it would be a significant bandwidth hit for them. Considering that MOST people have no idea what Usenet is, the ISPs have no interest in providing the bandwidth - especially for free.
However, you can subscribe to a Usenet service such as Giganews or Easynews and get full access. I think the total number of groups is over 80,000 at this point.
Another benefit of a service like Giganews is retention. Most ISPs will start deleting headers off their servers after only a couple days. So if you are downloading a massive multi-part binary file this could become a problem. You'll never find anything with all the parts.
A dedicated service typically keeps headers for weeks.
Best $10 I spend a month.