I learnt to write HTML files in the early 90's (The Geocities era as you refer to it - forget tables back then everything was frames). I learnt exactly how you surmised by using view source on existing websites.
As a 13 year old kid who was mildly curious I was able to build a web site for my high school by hand in 'pure' html code. It looked laughably simple compared to the web pages of today but it was easy. I can and did teach many other people to make websites the same way.
Nowadays it seems to me like you don't have a hope in hell of hand writing a website (maybe some people still do seem like an exercise in frustration to me). Everything is all frameworks and scripting languages.
Earlier this year 20 years after I wrote html pages for my school's web site I had cause to write some HTML again. I work as an engineer (the non software type) in an industrial plant. I needed to display some non critical data to our plant operators on a screen in the control room. I thought 'hey I'll put it on a web page'. It would save me from having to mess around with C which is what our HMI system is written in. So I built something using 1990's era HTML mostly from my memory (although I did move on to using tables instead of frames) It worked.
A few weeks later some one asked to make it possible to view historical results so I built a simple html form (also 1990's era technology) to allow user to input the date range he wanted to view results from. It worked but did no input validation was finicky about the format you enter dates into it etc...
A few weeks later I decided I'd modernise it - modern websites have things like popup calendars which allow the user to "pick" a date instead of having to type dates into a text field. I found a framework written in javascript which provided those sorts of things and attempted to use it. Seemed to work but a lot of subtle bugs kept popping up.
When you clicked on a date in the calendar such as 12th of January the framework passed it to the form in US style 01-12-2015 format I live in Australia we use 12-01-2015 as out date format. I could find no way to change the way the framework functioned. I searched google and a few other people complained about the same issue seemed to be no solution. I thought I'd dig into the javascript file try to edit the program to provide date in format I needed it to be in. The file was 'minified' impossible to read javascript. I gave up and modifed my script to assume US style date input instead.
Maybe I'm just to old to learn new tricks now but I miss the older simpler web sometimes.