Sadly not true. It's a nice ideal that some backyard animal raisers might get close to. But the meat industry produces huge and harmful quantities of waste at every stage. We all end up paying for the consequences of that waste to be dealt with.
https://www.colorado.edu/ecenter/2021/03/04/waste-meat-industry

hehe. You sound like you're getting very angry at this annoying vegan you've imagined. You're absolutely right that if a patient needs it, they're probably not in a state where you'd query it. But really, relax. There's millions of vegans, and few if any that would ever think of asking you for vegan EPI in an emergency. Whilst there are religious people who refuse life-saving medications, for most vegans, their principles are simply to make the less harmful choices where there is one, not to die for an ideology. And in a non emergency, what's so threatening hypothetically about a vegan asking if there's an option for a medication that's the more ethical choice? I use asthma inhalers, and requested the dry powder version rather than the aerosol. They're the same drug, but the aerosol is environmentally harmful. The doctor, nurse and pharmacists were all delighted to help. If they protested their assignment in treating me, I think they'd look a little crazy...

Again, you're not 'wrong' but the economics are not that simple. They once were... maybe still are in some places. But in the developed world, the economic model of industrialised animal farming is now getting weird. There is not such a direct line between the volume of meat produced (the primary commodity) and the viability of the business. You are saying that the value of the meat is primary because you couldn't derive sufficient value from the rest, but in Europe where I live, you usually can't derive sufficient value from all the products together! The industry is heavily subsidised, and the viability to farmers and to agrobusinesses relies on taxpayer subsidies paid per head of cattle, or per unit of land. So to the farmer/business selling the cow, its market value can't really be reduced to one product, even if it's the product with the biggest value. That's what I mean when I say that nothing is a byproduct. Every part that is paid for (including the subsidies) contributes to putting the business in the red or the black. If a quirk of the market meant that the most valuable part of the cow was, briefly, the gall bladder from which a powerful new anti-cancer drug was derived, vegans would probably not decide that meat was therefore a secondary 'byproduct' that was ethical to consume.