Teams is certainly a joke, it uses 400MB on my system idling in the background not connected to a single team, whereas Skype for Business running on the same system uses just 90 MB and does the same job.
This is just so that MS can save money on development efforts by shipping the same crappy web application to desktop and mobile users. I'm a developer myself, I certainly understand the benefits of writing an application once and shipping it to multiple
platforms. Great for startups, prototypes and getting things rolling. For a company like MS it's imho a bad choice, they should just put more effort in it and develop versions that are optimized for each platform.