Oofta
Legend
There are multiple ways around the issues. The encounters don't even have to be particularly linked.Eh, I don’t think it is that cut and dried.
Some DMs cut down on encounters for verisimilitude reasons (your 7th level party investigating a small town just happens to come across 8 encounters CR 4 to 10).
Some DMs want to keep the story bits coming quick and snappy, so adding extra encounters to extend the arc is a negative.
Some DMs vary pacing during the campaign, but find that while the standard DMG pacing works for dungeons, it doesn’t work in other circumstances.
Some DMs might be great at creating fun dynamic encounters when they are only creating 3 or 4 of them, but ask them to make 8 in a row and the quality suffers.
In all those cases, holding the DMs to a 6 to 8 encounter adventuring day does lead to encounters that are slogs, while a lighter pacing schedule (that is still quicker than gritty realism) would lead to an improved game.
Also, if a 6 encounter, 2 short rest is your MEDIAN, you are still looking at several 9-10 encounter days.
All I can say is I've been doing it since 5E was released. Ultimately I don't see it as an issue inherent to the system, it's an issue with DMs. There have to be some baseline assumptions on how the game works.