I agree, smokers are designed to accumulate grease and soot. Did you ever look at a commercial smoker and noticed how often they clean them...almost never when in continuous or semi-continuous use. Same with the flavorizer bars on my Summit 670. No rust as long as I use it; which is increasing a problem now that I have the SF.You guys need to get some grease in those grills. Mine is a big black grease ball.
This looks terrible, it means your barbecue accessories need to be replaced, I am using the Weber series of products now, there is no major problem at the moment, the quality is still very good, I bought it here-https://grillpartsreplacement.com/search?q=Weber&options[prefix]=last&type=product , If you encounter some problems and need to replace your grill, you can see if there are any products you need here, I hope my answer can help you, good luck!
Listen to none of the advice about sourcing new parts as bow.Mine has had plenty of grease in it, but I do scrape it into the drip tray regularly. I don’t do burn off but do cook high temps sometimes. These pics were after it ran at 500 for about an hour and I vacuumed out.