I love a matte box and filters, they’re great for creating artful exterior exposures, but some would say why bother when you can shoot Log and use grading software. And yes, those things really help a lot, but sometimes they can’t do it all on their own.
Cameras in them-days had a crummy contrast latitude (essentially the number of shades of grey from black to white) so it was very difficult to get a balanced exposure outside, the sky to bright, and the subject too dark, so you would use an ND grad (fading from clear to dark) to make the sky darker, giving more detail and contrast. If you were feeling fancy you could add a polariser, which when turned would make the clouds pop.
Nowadays cameras have a much wider contrast latitude ursine Log looks, so there’s more detail in the highlights and lowlights, but I’d say there still isn’t enough. Especially as Log looks best when over exposed, so you lose detail in the highlights and once those details are gone, no amount of grading will get them back. So you may need to squeeze the highlights down to get the detail in a high contrast situation.
Trust me, if you’re shooting outside and you want the sky to pop, it’s definitely worth getting the matte box out and mucking about with filters. Here’s a project where I did just that and I’m glad I did, as this moody sky looks great in monochrome.