Secondly, you’ve combined app categories that don’t fit. Google+ was a social network, Hangouts was a chat app

Hangouts was originally part of Google+, hence "Google Hangouts (2013), which was part of Google+ (2011)"

If you don't recall it as a feature without G+, then at least trust an article talking about it.

Hangouts was third, a real-time video chat product embedded in Google+.
The Verge (2013) EXCLUSIVE: INSIDE HANGOUTS, GOOGLE'S BIG FIX FOR ITS MESSAGING MESS

Finally, you’ve conflated technologies. Android Automotive OS is an entire OS running in a car that is maintained by the OEM in much the same way as Android is on phones.
...Incidentally, this has nothing to do with Android Auto, which is an extended display for your phone.

I mention both as they are intended to provide the same functionality, regardless of the underlying technology -- integration of a vehicle's Infotainment with a Google provided ecosystem. In-fact, Android Auto apps are compatible with Android Automotive, because, technical 'why' aside, the function to the end-user is the same.

Google has been around for 25 years and always has chased innovation. They create a ton of things, see what sticks, then iterate or pivot.

According to many Googlers over the years, the reason many of these projects eventually discontinue and fail isn't because things 'aren't sticking' but rather due to the internal culture, in that to set yourself apart and get good performance ratings, you must always strive to be on teams that are doing something new. This leaves little to no resources for maintaining the 'old' regardless of how much people like them (or not).

While I too have been frustrated by the discontinuation of service I liked

I don't know about everyone else, but I wrote, what I wrote, not because I'm frustrated about a discontinuation of any service I liked from Google. That happens. It is because the branding and evolution of products are confusing and at times, they even coexist for some time. From my perspective, it often seems as if there is no actual long-term plan or guidance for many services that have come and gone with no signs of that changing.

The perception of the chaotic mess that Google brings with many of its services past, present and probably the future is at least something that I felt I wanted to criticize. They deserve it regardless of the supposed intentions behind the curtain.

Whenever I hear this kind of complaint, it sounds to me that people just want Google to be more like Apple or Microsoft and churn out minor improvements to their existing money makers with minimal innovation.

That's your opinion I suppose but it is not mine. My opinion is that Google should at least change the perception of their products to have clear and clean plans as they evolve. This would give me a reason to trust their branding more.

You mentioned Duo and Allo, which co-existed along with Hangouts for a time. The utter confusion and lack of interoperability created a confusing schism within the same userbase that used them at the time. You could argue that somehow they 'innovated' chat and video conferencing but they didn't even call one something like Hangouts Chat and Hangouts Video when they segregated the functions with a clear passover from Hangouts itself.

I think people would just prefer Google appears to be less arbitrary and in disarray about their products. If we are to believe some of the people that actually worked on these products, then that is going to require a culture change within.