I’ve been using Linux since 2004 and have seen and used a lot of Ubuntu based systems. I first started out on Ubuntu 10.04 and coming from a Windows XP Desktop to something new and boy it was fast. I agree with you, that Ubuntu is heavy and that is because, technology has moved on, since the early years of computers. With it comes an even heavier Kernel packed to the brim, with security, codes for USB based Hardware to work out of the box, like in Windows. Ubuntu never used to be like this, gone are the days where you have to compile stuff yourself to get things to work, when the majority of the hardware support is included in the kernel, which comprises of nearly fifty to sixty trillion lines of code and that is not including the OS itself. That is just a guess by the way of the amount of code in the kernel, it’s probably way more. Back when Ubuntu was Gnome 2 and looking the way that Ubuntu Mate looks today (Apart from it being the color green.), to get anything working USB wise, we had to compile it ourselves and not knowing what to do, we looked out for the great support on Ubuntu Forums and nine times out of ten, we would get the answer, from the general public with scripts that were posted to install the drivers we needed. That’s one of the reasons why people were put off of using Linux, cause all they heard was that you need to know a bit about programming, to get Linux to work properly.
Those days have nearly gone, depending on the hardware you’re trying to use or get working, WIFI drivers is still a pain and will always be, hence why I don’t do WIFI fully plugged into my Router, it’s safer.
Microsoft used to dis Linux, till they realized how good Open Source Software really is and they bought a seat on the Linux Board, Canonical are in partnership with Microsoft in some small way too and we are all to blame for this, whether you like it or not? As over the years we moaned that drivers, games and other things that do not work properly, so once Microsoft bought their seat and added their bit of code called money, the kernel as we know it is absolutely massive, hence why Ubuntu feels heavy, cause it is bloated out, but again depending on hardware you’re running it on. SSD drives were invented to speed your OS up, without having to rely on defragging the drive all the time. Linux was invented, to take away the proprietary system’s hold on the market, but even today, only a small handful of people actually know, what Linux is? It started as one line of code, which was then handed to the public to build upon, but we have lost that some where along the line. The biggest change of course in Linux, is the software running on it. Gone are the days when Open Source Software kept crashing all the time, as Linux users began to get to know their OSES and in short what their machines are capable of doing. The latest hardware for a gaming machine and intense video editing managers, astounds me that Linux can run on these types of hardware and that is why the kernel is so big, that you can install Linux on nearly any Hardware you chuck at it. Gone are the days where absolutely nothing would work out of the bag too, with so many Ubuntu based systems out there, with their own spin of a Ubuntu based system, whether it be XFCE, LXDE, Budgie, Cinnamon, even Debian, which Ubuntu is based on, but not fully. Here in 18.04 look at all the software we are now able to get our greasy paws on, without having to add PPA’s well hardly. Years ago and even in 16.04 you still had to add PPA’s to get the software you wanted, but Ubuntu have now made it easier, with either a sudo command, flatpak, synaptic, (Which is the best package manager in a Ubuntu system), Snaps. The world is your oyster as they say.