It looks like a bunch of older markers have feed tubes that are angled 45 degrees (rather than being vertical). And the accepted hack today is to get an angled feed tube that makes the final position vertical in order to use modern hoppers (at the cost of excessive height).
It isn't a "modern" thing people have been using elbows for as long as they have been making 45* feednecks. They have always used elbows since feednecks were invented. Also, its not really excessive, Ever seen an Impulse? No not the new one the original one, It sits super high, and its center fed. A lot of the old "classic" semi autos have massively tall feednecks.
My question is, How were these markers supposed to be used when they came out?
Did the makers expect everyone to get an angled feed tube?
Yes, They usually came with one. You could always use a spring feed or a feedtube as well.
Or was there a different ball feed technology that works well with this angled feed system?
Powerfeed. Many Automags have a plug in their feedneck you turn to angle the balls into the breech
I am really asking because there are cool looking pumps that have this feed but I do not relish the idea of a hopper WAY above the marker...
Use a Springfeed.
There are modern day Spyders that use straight feednecks that sit much much higher than a lot of 45* markers.
Its still fairly commonplace, many Spyders, Tippmanns, and BTs still use 45*.
Here is a nice old video by Sugarstump that'll show you some old school goodness.
Before feednecks were around everyone had SC guns (Then just guns) and they would put really long feedtubes on top.
Here's a picture of my PK45 on my KPMI. It was a PMI-1SC but I did work to it.
Hopper hits, gun hits and headshots didn't count for a long long time, so it didn't really matter. Everyplace had its own rules about hits though.
A VM68 - Probably the tallest of the bunch because of the odd feedneck detent system it used.
My Sniper II, I usually use it with a spring feed.
My Sniper I
A Palmers Stroker - This one sits extra high because the original Sheridan feednecks had you stuff the hopper into it. it has a sleeve so that you can use a feedneck.
A ULE AutoMag - Probably the lowest of all the profiles pictured.
And my Friends stock eNMEy -