Paul Ryan is Chairman of the House Finance Committee and the House is the originator of all fiscal legislation, so that makes him a very important person vis-à-vis the other 434. If you are a "freshman" Senator you are not all that much above a page...You have to wait for one of the 99 fossils to die before you can hope for a committee appointment let alone a chairmanship.
Regards,
GtG
Yes I know, just like the democrats it is not about doing for the country, it is all about the position.