I think the difference is really more noticeable if you're on a limited connection. For example, on Starlink I only have 50 GB to play with. It's entirely ineffective if the browser downloads the ads and only scrubs them out of the view after the fact. Same with anybody using a mobile hotspot over LTE. In those situations bandwidth is super limited (I have 5 GB of hotspot data a month) unless you can convince the carriers to zero-rate data pulled for advertisements (they won't) I'll continue blocking ads before they can be loaded.

Edit: and I'm not on some cheap MVNO, I'm paying over $80 a month with AT&T on their post-paid plan. The phone gets unlimited data but any other device I may need to share that connection needs to be as efficient with bandwidth as possible. Only Firefox and derivatives provide proper ad blocking at this time.