But today, in 2024, if you just standardize on AWS, you can pretty much use one of the AWS services for pretty much anything. And that AWS service will be already distributed in the backend, for free, in terms of you not having to worry about it. Additionaly, it will be run by AWS engineers for you, with all sorts of failovers, monitoring, alerting, etc, behind the scenes that will be much better than what you can build.
So these days, for 99% of people it doesn't really make sense to worry too much about this theoretical stuff, like Paxos, Raft, consistency, vector clocks, byzantine failures, CAP, distributed locks, distributed transactions, etc. And that's good progress, it has been abstracted away behind API calls. I think it's pretty rational to just build on top of AWS (or similar) services, and accept that it's a black box distributed system that may still go down sometimes, but it'll still be 10-100x more reliable then if you try to build your own distributed system.
Of course, even for the 99%, there are still important practical things to keep in mind, like logging, debugging, backpressure, etc.
Another thing I learned is that some concepts, such as availability, are less important, and less achievable, then they seem on paper. On paper it sounds like a worthy exercise to design systems that will fail over and come back automatically if a component fails, with only a few seconds downtime. Magically, with everything working like a well oiled machine. In practice this is pretty much never works out, because there are componenets of the system that the designed didn't think of, and it's those that will fail and bring the system down. Eg. see the recent Crowdstrike incident.
And, with respect to importance of availability, of the ~10 companies I worked at in the past ~20 years there's wasn't a single one that couldn't tolerate a few hours of downtime with zero to minimal business and PR impact (people are used to things going down a couple of times a year). I remember having outages at a SaaS company I worked for 10 years ago, no revenue was coming in for a few days, but then people would just spend more in the following day. Durability is more important, but even that is less important in practice then we'd like to think [1].
The remaining 1% of engineers, who get to worry about the beuatiful theoretical AND practical aspects of distributed computing [because they work at Google or Facebook or AWS] should count themselves lucky! I think it's one of the most interesting fields in Computer Science.
I say this as somebody who deeply cares/cared about theoretical distributed computing, I wrote distributed databases [2] and papers in the past [3]. But working in industry (also managing a Platform Eng team), I cannot recall the last time I had to worry about such things.
[1] PostgreSQL used fsync incorrectly for 20 years - https://news.ycombinator.com/item?id=19119991