Proof-of-work (PoW) mining is what permits bitcoin to be resistant against centralized control.

Mining exists to cement the ordering of transactions.

That's it. That's the entire reason that Bitcoin mining exists.

That means neither any government, nor any mining pools or mining cartels with less than 50% of the hashrate have the ability to change the ordering of the transactions.

In over a dozen years, there has never been a transaction ordering issue outside of a single incident in 2013 when a new release of the software changed the behavior and a chain split occurred (and one person used that opportunity to change the ordering of his transaction such that an exchange got cheated on a confirmed (six confirmations) deposit transaction that no longer existed when the chain split got resolved (i.e., the ordering of the transactions was changed).

While there are shitcoins with PoW mining as well, those are not as resistant, or are unresistant -- due to them requiring a significantly smaller set of resources in order to pull off the double spend attack. Even a determined attacker (e.g., the U.S. gov't) would not be able to pull off a mining attack against bitcoin (at least, not one that would be a surprise when it was executed).

As far as an article on it ... the following explains the double spend problem. But it mentions "mining" exactly zero times: https://www.babypips.com/crypto/learn/what-problems-did-bitcoin-solve

But try to find a way to solve the double spend problem without PoW mining and you end up with crap like proof-of-stake (e.g., Etherium) which doesn't actually solve the "multi-dimensional problem of decentralised consensus that Bitcoin and its Proof-of-Work-based consensus mechanism solved".

Grandpa probably can't or won't do the research to truly understand why bitcoin mining must exist, but maybe he can understand that if there was a way for bitcoin to work without bitcoin mining and be just as resistant to centralized control, that would have occurred by now. And thus, we embrace bitcoin the way it is -- because there is no alternative.

Any TL;DR: ?

But most miners aren't set up to power off when the grid needs additional power -- except for some in Texas, and maybe a few others elsewhere. It is technically possible to do, most everywhere, but there is investment and operational costs borne by the miner to make that happen, and essentially no benefit to the miner for doing that -- unless there are agreements in place benefitting the miner for not taking that power.

What is missing is the desire by the producers to take advantage of this opportunity to make use of this "rolling reserve" power source. That may come eventually but the generation plants quite like it being able to charge whatever they want and not have to partner with (i.e., rely on) anybody else to help with the supply.

See the introduction, here:

Running a solar-powered Bitcoin/Lightning Node & Lottery Miner — Introduction #201134 https://medium.com/@ne0nblack/running-a-solar-powered-bitcoin-lightning-node-lottery-miner-introduction-12005bd06960