This has not been my experience, at least not flying domestically in the US. In order to get to the gate, I have to get past TSA and the security checkpoint, which involves presenting my boarding pass and ID to an agent.
If I've not checked-in electronically and have to get a printed boarding pass, I've had to present ID and credit card at a kiosk or ticket desk as well.
They ask for it but you don't HAVE to present it. If you don't most airlines will ask you identity verification questions, similar to those you're asked when retrieving your credit report. If everything matches up your ticket will get marked with SSSS[1] and you'll be sent through that additional security.
If I've not checked-in electronically and have to get a printed boarding pass, I've had to present ID and credit card at a kiosk or ticket desk as well.