When I see this, I suspect the vendor is operating under conditions that approach absolute chaos: dumping whatever junk someone imagines might be necessary into the stack with zero resistance, for years on end. Zero effort spent on any factoring that might threaten redundancy.
I'm not saying the tools aren't bloated, but I believe that a lot of the size (sorry, can't quantify right now) are the datasets for each and every FPGA model that the tool supports. This includes, among other things, timing information for every wire in the chip. You really only need the files for the device that you are targeting and you do have the option to install only that, or you can install larger groups (e.g. same family, same generation), all the way up to installing every device that ever existed that the tool supports. That's how you get to hundreds of GB.
Are you sure about that, or is it just a guess? If that is the case, how will the open source toolchains avoid the same problem when they eventually become the industry standard? (I can imagine something like a software repository for serving device-specific information on demand.) Are they planning anything right now?
Xilinx toolchain installations used to include a file which was just the concatenation of the license files of every single open source library they were using somewhere inside any of their own software. Now if you installed two or more components of their toolchain (for example, Vivado, Vitis, and PetaLinux) into the shared installation directory, this same file was installed several times as well. Together, they made up something like 1.5 GiB alone.
Welcome to modern development lol. Try to refactor it and get an answer of "no money for testing".
On top of that, the "agile" mindset all too often also means there is no coherent vision where the project should go, which can and does lead to bad fundamental architecture decisions that need extensive and expensive workarounds later on.
And yes, there have been people describing exactly that in ASML [1], although the situation seems to have improved [2].
When I see this, I suspect the vendor is operating under conditions that approach absolute chaos: dumping whatever junk someone imagines might be necessary into the stack with zero resistance, for years on end. Zero effort spent on any factoring that might threaten redundancy.