Sort of. You can view live TV via OTA, and that is free. An HTPC is simply a computer. So whatever you can stream on your computer today, you can also stream on an HTPC. If you subscribe to cable and get a cable tuner for your HTPC or get an antenna and an OTA tuner, you can also view/record live and play back recorded TV. If you can find the content you are looking for on the PC you are posting from, then you can also find and stream it from an HTPC.
Everyone has different uses and requirements for their HTPC's, but I think it's safe to say the major uses include cable DVR, streaming services (Netflix, Hulu, Pandora, etc.), and file streaming (rips, mkv's, torrents, home videos, music). The primary reason I have an HTPC is not to avoid paying for TV entirely, but only to save about 50% off my cable (or satellite) bill by not having to pay DVR fees. If I were satisfied with OTA network TV and streaming content like Hulu and Youtube, I could do away with my cable TV subscription entirely.