You are talking to a guy who works with video. And streaming is like VHS SLP; it’s acceptable for your average consumer, but it’s extremely poor quality when compared to Blu-Ray/4K Blu-Ray or the original studio masters. Blu-Ray/4K Blu-Ray is like Laserdisc, while DVD is like S-VHS SP.
I work with 1.5gbit HD and 12gbit 4k, you don't get much higher bitrate than that. We do have some quad-sdi (we live in a legacy world, and throwing some sdi cables across the lot is far safer than trying to share IP between different production vehicles), but on the whole 4K is streaming - mainly 2110 (some 8 bit, some 10 bit, and I mainly work in 50 rather than 60 so bitrates are a bit variable), some 2022-6. Working on our forward looking architecture and I don't envisage any SDI routers beyond small routers (40, 64, maybe 128 in large trucks, if we build any more). Certainly we'll have one or two A/B 2110 leaf/spine networks instead of two 1500-square sdi matrices by the end of the decade, or we'll be even more decentralised than we are now.
The highest the spec goes for 4k bluray is a measly 144mbit, that's nearly 100:1 compression compared with streaming.
I don't do much in the way of 4k compressed - still have relatively few events generating it (and this year events are rather short on the ground - although looks like Tokyo and Amsterdam are on), but 50, maybe 100mbit h265 are the ballpark numbers of what's usually considered to be high quality.
The last major event streaming I did in October was plain simple HD at 60mbit h264 (2 RTP streams with a video payload of 60mbit, about 6mbit of audio I think - it was dolby-e pass through, and some overhead of course). Could have gone higher, but it's not necessary - even with the transmission chain, in double blind tests people can't tell the difference.
So Streaming vs Disk
Streaming vs Disk is not what determines the quality, nor indeed is bitrate (although obviously bitrate is linked). You'll get far better quality out of a 10Mbit netflix source stream with multi-pass encoding h265 than you will with the same material on a 12mbit blueray encoded with h264, but you won't get better from a blueray 20mbit stream than you will from a netflix 20mbit stream with the same encoder and settings. It's all data, doesn't matter how it's transported, what matters is how it's generated and decoded.
The level that someone can tell there are artifacts varies, and I'd agree that there's plausible an impact in the window that netflix are claiming (did I see topping out at 12mbit for 4k? That feels low to me, even with a specifically tuned encoder) - and I think that in any case reducing the top bitrate is a shot in their own foot given their audience, the ease of measuring bitrate, and the difficulty in measuring quality, but that's not a streaming problem, that's a business decision from netflix. No reason that you can't stream 50mbit or 100mbit, it's a business decision
Any measure you can use to objectively measure quality (psnr, ssim, vmaf) can be quite trivially rigged (see arguments at events like demuxed), so "bitrate" is the only thing people have to compare. Which is a shame, as a good h265 encoder at 20mbit will trounce a poor h265 encoder at 40mbit. At decent bitrates your viewing setup is far more important though.
If you want to measure quality, you need to do large scale double blind subjective experiment with a variety of sources (not just things like the EBU test tape), following ITU-R BT 500, and even then you still wouldn't win over audiophile types (the ones that claim they can hear CD 'compression')
Enjoy your blurays. I know where you're coming from with complaining about "streaming", and I've seen some awful streaming in the past (the final battle of Winterfell in GoT on nowtv was awful, was about 5mbit in HD. I cancelled shortly after that), but ultimatly the convienience and the power of streaming will prevail and those bluerays will become rarer at time goes on.