For more modern English, I think George Orwell is very hard to beat.
For blog posts, Paul Graham is always worth reading - not so much for the content, which is often debatable, but for the style, which is reliably lucid.
But it's always a good idea to match the social register and jargon level of the target audience. Professional writers often work on a range of gigs and know how to mould English into a range of styles and voices to reach different audiences.
So I'd be skeptical of any suggestion there's a One True Style for online content or technical writing. There are certainly common standards and traditions, but they may be out of date or too company-specific to apply generally.
I am a native English speaker and I was confused on the first pass when reading quickly and ignoring punctuation.
Reading slower and taking pauses at the commas allowed me to understand.
I think that minimizing the use of negatives and pauses helps the reader absorb the information quickly.
I don't think that's difficult for educated native English speakers. Walden was written in 1854, and most people who went to high school in an English speaking country would have some exposure to Shakespeare which is 250 years older than that - so I really don't think it's very archaic. Are you a non-native speaker? You write English completely fluently but if you've had no real exposure to the literature I can understand why you might find it hard going.
I haven't taken English since high school, and had no "liberal education" at university, and I did just fine with the audiobook (ie the whole thing was read aloud to me). I am not going to pretend it's easy to understand as modern, informal speech but it certainly wasn't arduous.