[spoiler]

The problem is multi-faceted. There was a YouTube video from a few years ago that explains this[1]. But, I kind of empathise with you; I and some friends also have this issue sometimes when watching things.

[1]: https://www.youtube.com/watch?v=VYJtb2YXae8

[1970-01-01]

It really isn't. I've never, never had a hard time hearing the voiceover whenever the ads decide to intrude. Sound editor and mixer is a full time job. The audio problem starts and ends with them not doing their job. If the source is mumbled, the experience needs to be fixed in post or redone. Else garbage in, garbage out. It's only multi faceted in regards to letting the quality of the finished product slip on every check down the line.