They are allowed to propose laws (and amendments to bills). However, the House and Senate leadership has control over the voting schedule. There are still way

They are allowed to propose laws (and amendments to bills). However, the House and Senate leadership has control over the voting schedule. There are still ways around it (e.g. https://en.wikipedia.org/wiki/Discharge_petition https://en.wikipedia.org/wiki/Discharge_petition), but they are not particularly fast and the legislative calendar is crowded. Worse yet, these measures also stick it to leadership – a plucky Representative has to not just want something, but want it badly enough to embarrass the rest of their party. That’s rare.