What does everybody use for molded capacitor replacement?

[CJVx]

I’m talking about rectangular caps that are often similar looking to mica caps, domino etc. apparently they are molded paper capacitors, mostly in picofarad values and are often times in a mode of failure just like standard looking paper capacitors. I’m reluctant to use ceramic disc capacitors in place of these since most sets have plenty of ceramic disc capacitors in them already, so why wouldn’t the manufacturer just use them for these applications. Thanks.