Michael is right. For the entire HF spectrum, you don't need RF stages in order to conceal mixer's noise: noise picked up by the antenna is stronger. Wes Hayward W7ZOI has been publishing articles on this since the 80s.
And you don't need active stages to get selectivity against image frequencies either, a double or triple tuned passband can be placed right begore the mixer.
On the other side, adding RF stages before the mixer decreases the receiver's dynamic range: makes it easier to be overloaded by strong signals some kHz or tens of kHz apart from the desired one.