Legit good question. US Congressmen clearly know, work alongside, and secure funding for lots of grants (in the Delta, in Mississippi, and in the USA). For anyone to suggest they are all-powerful or even close to it is close to laughable. I'd guess 85% of people can't name their congressman or give 1 single solitary rat turd about them.
Bennie has a little more influence being the only federal or statewide elected D official in Mississippi. But, like, that doesn't make you MORE powerful. Bluntly, I'd rank him at best as middling congressman overall and I'd likely agree with someone suggesting some fresh blood could be a good thing. Incumbent politicians are really really hard to replace