Waiting 5-10 minutes extra on a single ride isn't a big deal for guests who only ride a single ride during their day at the park, but exceedingly few people visit the parks in that manner. Most come and spend a large portion of the day and try to ride multiple things, and those increased wait times have a meaningful impact over the course of a day.
And while 5-10 minutes doesn't seem like much in isolation, using your numbers from the DL thread jumping from 30 to 35 minutes represents a 17% longer wait. When guests already spend several hours each day waiting in queues, having them spend 17% (or more) longer is a significant change.
Additionally, it cannot be overstated how much better equipped DLR is to distribute crowds, despite its more compact layout and smaller queues. Using the number of rides as a shorthand for "things people wait in line for" (since line-skipping is functionally worthless at walk-through and theater-based attractions, where there isn't a linear queue), Disneyland Park has 37 rides, 14 of which have a line-skipping option, 23 of which do not; DCA has 17 total, 9 with LL, 8 without. If guests want to ride things without being directly impacted by LL slowing down the queue (though it inflates wait times across the park), there's still a variety of attractions to choose from.
Meanwhile in WDW, MK generously has about 24 rides (including the currently-closed Big Thunder, seldom-operating Main Street Vehicles, and soon-to-close Liberty Belle & Rafts to Tom Sawyer Island), 17 of which offer line-skipping, and 7 do not. Epcot has 12 total rides, DHS has 9, and DAK has 7; across those 3 parks, a total of 2 rides (Friendship Boats & Wildlife Express) don't have LL.
Visitors-per-park are roughly equivalent between both resorts, but WDW has fewer rides for them to visit, resulting in longer lines. WDW further compounds this issue by having far fewer rides without LL, making the already-long waits even longer with fewer "pressure relief valves" to easily absorb crowds. And to top it all off, WDW's parks have much shorter operating hours (using today as an example, WDW's parks average 11.75 hours of operation each vs. DLR's 15 hours - 28% more), making a guests' time an even more precious commodity.
So, sure, 5 or 10 minutes here or there isn't a major change. But over the course of a busy vacation in crowded parks, it can result in hours of additional waiting, which will meaningfully impact what a guest is or isn't able to experience during the park's operating hours. Disney isn't in the business of providing a great experience, they're in the business of making its customers just-miserable enough that they're willing to pay extra to make the already-expensive parks slightly more bearable.