It is easier for a modern user to ask in a chat (and get angry that they are not answered quickly) than to read instructions.
Because the corporate world is 90% "to talk" (meetings, zooms, Skype) and 10% is "to do something."
Because a child and an adult assembles LEGO not according to the instructions, but as he wants.
Because if the lack of instructions prevented the sale and use of the box, then the instructions would have been there a long time ago.
Because bugs in software are a normal process. The chromium engine that Chrome is built on, 1,100,000 open bugs, and these are bugs from Chrome developers to chromium engine developers, not even user bugs yet -
https://bugs.chromium.org/p/chromium/issues/list