Ok. Let's just choose a date that we can all associate with, 1878 - the introduction of the close season (even though I'm not in favour of it as a modern day tool). Prior to that anglers stood back from any organised protection of the fish (all coarse fish that is) and to some extent they didn't need us. Anglers hunted them, but we were only there in small numbers relatively speaking and posed little threat.
Going back even further, there weren't anglers as we know them - AND - hardly any industrialisation around the river systems. No harms and no threats meant no one even bothered about fish so they were left to their own existance, pike being top predator survived better than most. You can go back then through the middle ages, back through Biblical times, back even beyond the ice age and pike had no threats from the outside hence it's true that for millions of years, they didn't need protection.
However, since the early 1700s and more particularly after the invention of the steam engine, this country has become more an more industrialised and because of better health and diet, more and more populated. Sufficient to say that it cannot help but put pressure on rivers and other sources of water so that now, more than ever, all fish (don't set aside pike) need our help to keep an eye on the rivers etc. If we turn our backs for one year, there will be uncontrolled mayhem, water companies wanting to do 'self-monitoring' (yeh?), bypass sewage systems (Thames Water), and companies wanting to just dump poisons into the sewerage.
Times have changed in the past 200-300 years, vastly. Just think about it for a moment. That's why we need to look after the fish we catch, and protect all the fish we don't catch. To do this, you could do no better than join the Angling Trust.