I would say that article is helpful - but also misleading.
I have one problem with that article - which is that it conflates "lossy" with "not bit perfect".
The two terms do not mean the same thing.
In general usage the term "lossy" refers SPECIFICALLY to audio CODECs that DELIBERATELY use some form of "perceptual compression" to save space.
For example MP3, AAC, and Ogg Vorbis all deliberately reduce bandwidth and file size by discarding information that is "perceptually unimportant".
(In other words they save space or bandwidth by discarding information that that they hope you won't notice is missing - much as JPG does for images.)
The term "bit perfect" specifically refers to having an exact bit-for-bit copy of the original data.
So, since bit-perfect data is an exact copy of the original, it cannot possibly be lossy.
Therefore, making sure you have bit-perfect data is an excellent and simple way to confirm that what you have is lossless.
HOWEVER, it is quite possible for data to be NOT bit perfect, yet still NOT be lossy.
For example... If you up-sample a 16/44k CD to 24/96k then it is no longer bit-perfect... but it is also not lossy...
It isn't "better than the original"... because it cannot possibly be more accurate... but it isn't specifically worse either... it just isn't the same.
(And, since it's different, you may feel free to "decide perceptually" whether you like it better, or not, or cannot tell the difference.)
And, if you've ever listened to an "MQA stream" on Tidal, which originated from a non-MQA CD, then that was NOT bit-perfect either.
(MQA processing by definition alters the bits - so, by definition, the result cannot possibly be bit-perfect.)
If you read the article you will find that the author actually contradicts his original claim...
In fact he says that "the Bluesound Node 2i successfully streamed lossless audio from Amazon Music HD from 16 bit / 44.1 kHz up through 24 bit / 192 kHz".
So, according to the author, the actual music stream coming from Amazon is in fact - or at least can be - both bit-perfect and lossless.
This would seem to offer proof that the data itself is not compressed to save bandwidth.
HOWEVER, WASAPI mode is the bit-perfect lossless audio mode that is offered in recent versions of Microsoft Windows.
And, the last time I looked, the Amazon Windows 10 player client still did not support WASAPI mode... while, in fact, virtually all other "lossless" services do support it.
This means that the Amazon Music Windows Client is not bit-perfect.
I don't know... but I suspect the OSX client is similarly not bit-perfect.
(Unfortunately very few other streaming devices or apps support being able to play the Amazon data stream.)
I would absolutely agree that this seems to be a significant OVERSIGHT or OMISSION on Amazon's part.
And a lot of people have been complaining about it for a few years now.
However, claiming that Amazon Music is lossy is overstating the actual facts.
As far as I know Amazon does not use any form of intentional perceptual compression.
However, since they fail to provide a bit-perfect data stream, the only way to judge their sound quality is with your ears.
I should also mention something that an awful lot of audiophiles seem to forget...
EVERY SINGLE DAC ON THE PLANET IS 100% LOSSY.
All of the digital bits have been replaced with an analog signal that is hopefully an accurate representation of the data they contain.
I personally prefer Amazon Music because of the selection and the stability of the streaming itself...
And I cannot say that I find it to sound significantly different than the original (in the instances I've actually compared them)
I've also used both Tidal and QoBuz...
And, at least on our office network, both had more occasional dropouts than Amazon Music...
But, more importantly, with both, there were a lot of albums I wanted to play that they simply didn't have...
(And, at least to me, if I can't play the album I want to listen to, that counts as "100% lossy"...)
I cannot say that even Amazon has every album I might ever want to play...
But, so far, for me, they have a far better record than anyone except possibly Spotify...
And, so far, Spotify does use lossy perceptual encoding, which is sometimes audible...
(Although I hear that Spotify is again promising lossless streaming in the near future.)