Excuse the long reply, but I totally get where you’re coming from. There are probably 2 huge reasons why it’s used in a lot of games that require repetitive tracking/scoring. Coming from the dealing with costs and vendors directly in the past and also having a card game with a stylized paper tracking component, I’ve broken it down to two things; cost and consumable.
As you mentioned, the manufacturing costs involved is probably the number one reason. There are many ways to track game stats and scores, and I’m not just referring to older games, but newer games as well. One could create different ways to track score with components, but RPGs and tabletop sim on the whole require a card and coins/chits/block or custom counters to be produced. It’s inexpensive to to go paper versus custom counters. This, as minor as it may seem, can run up the cost per unit. I’ve dealt with some vendors back in the day and it does add up. Designers can keep the pencil/paper feature out of their games all together but that margin is minuscule compared to custom tracker vs. paper tracker. I say if the costs mattered that much to the designer, just inform the gamer to use their own stuff. Lots of games do that too. I’m sure we all have paper and something to write with kicking around to keep score. Heck. We all have cellphones to do the same thing. Paper and whiteboards not necessary.
The other condition I see is revenue on consumables. They are usually seen as a replenishable asset. This is a way for a company to make a little bit of money and the gamer keep the original experience recorded in the intended format. Yatzee and Scrabble are prime examples of this. Respectively, I see this more so in commercial games than indie productions or small game production. It helps keep a very tiny recurring revenue for the publisher. Now, that being said it’s probably the least thing to be concerned about. There were and are games that use coated boards/scorecards for dry erase that are built in now, and have been since the 80s. I have a couple old board games that had wipe down boards instead of paper sheets.
At the end of the day it’s a personal preference. I don’t feel a ways about having a paper record of my game play or stats if it means recording my experience on something I can keep. Also, if the scorecard is formatting for organizing and tracking stats and tracking and can be customized by the player (ei: DnD and other sims), then I would have sheets over whiteboard. General tracking of position, order, or numbers to tally at the end of the game should more than likely be done on a renewable surface. Your opinion is valid, but at the end of the day it’s a player to player thing.