"ideas aren't patentable"

That's true, but business methods and certain software implementations of novel ideas are patentable...at least in the US. I've found that truly good ideas are easily translated into one or both of these. The problem is, most people have "me too" ideas.

All philosophical arguments aside, the patent system can be an entrepreneur's best friend. Yes, the system is heavily abused. I personally don't believe in software patents. But I damn sure use them. Color me hypocritical.

In the theoretical law where statute is obeyed and Supreme Court precedents are followed, you're absolutely right. For the actual law that happens to you when you go to court, you should consult a lawyer.

For better or worse, this is incorrect.