This is the same story I've heard for the past 50 years.
It was always better 10 years ago,.. 20 years ago,.. thirty years ago,.. blah blah blah,.. when I was a kid,.. blah blah,..
It wasn't.
It was exactly the same.
When you were a kid you were a foot shorter so the waves were foot bigger.
When you were a kid you were scared of any wave over two foot high so they were all monsters.
When you were a kid your total experience on a board was one or two years so every wave was wildly exciting. Now, the same size wave is just boring.
As to whether years ago the waves were always better down south,.. or up north ,.. or over east,.. or west,.. or anywhere but here,.
There were days when you would drive down some blistering hot sand track to get to some secluded spot where the waves were supposedly always brilliant,. only to find they were... non existent,.. flat,.. barely a ripple.
And there were days when you would rock up to some ordinary spot expecting nothing and it was totally ripping.
Now, on the days when the swell is less than ordinary we choose to remember the few days when the waves were exceptionally good and compare them to that.
On that basis, the waves of today will always be worse than what used to be.
The comparison is not valid and the conclusion drawn by making it is false.
I don't think the average conditions have changed at all.
Some days good, most days average, some less than average.
But,..they are all good days for something, but maybe not just what you had in mind.