No steam DL manager was not perfect, they possible learna thing or 2 doing corona with many people was home and mass DL.

And your connection issue with a ISP, is not a steam problem , most have flatrate or broadnand todsay they dont have a ration DL issue anymore.

And most online games here, do not a monthly DL limitation, so maybe steam change this old wasy because its outdated.

I'm sure you do not like the reply, but gl with ask steam support if they actual have other reason i cant see it, even if they reply you with it. ( modem age we other had with pay per minute is gone. ) or other bandwide ways explanations from mobil crap ISP deal's.

Dont forget you talk with many steam fiber solutions today, we have 24/7/365 no restriction.
why will steam not adapt to that.

You also forgot try learn use DL schedule, in off peak hours then it suit's you,

This is the future, IT company have done this over 3-4 decads, update and fix PC and servers doing off peak hours, why will gamers not do same then they have more time to play, instead of sit and wait for DL and installment, to be funny or rude might be a way so other learn more time to play instead of sit and wait for peint to dry´, ( aka be done with DL and installament and opotion you actual have no choise's in anyway ) just wait to more ppl get it, we do not sit and look at DL and instalment anymore, that's a waste of out time. ( wait to you have job and kids, then you have no choise to be effective with the little spare time you might have.

As i said welcome to the future.