I find internet writing to be stimulating in its own way precisely because it is a sort of dash-off writing that does not need to be as precise or exact as would be needed if you were seeking to meet professional standards.
To wit, in law, even in formal contexts, lawyers dish off all sorts of slop in legal briefs, etc. but this really is sub-standard lawyering. To do your job right, you need to meet standards of excellence in making sure you have sound analysis, careful factual recitation, and skilled application of law to facts as you make arguments or seek to achieve some other professional writing goal. This is true as well in less formal professional settings such as writing emails/letters to clients. It may not absolutely matter what you say in terms of precision if a client is not likely to pick up the fine points but it really does matter in terms of maintaining a consistent pride in your professional work. Slop is slop and, when people will evaluate you by how well you are representing a client, it is critical not to be slipshod in your writing.
When writing on the internet, in contrast, you of course want to avoid putting out slop there as well but a lot less precision is needed to make your points. If you make a legal point, it is implied by context that you are making a statement that may not be accurate down to the finest level of detail, that you may be simplifying, or generalizing, or simply venting an opinion that the law may or may not support. Law in itself will vary, even greatly, from jurisdiction to jurisdiction, and this means that much of what you may be saying is really setting forth broad principles while avoiding a specific application to a given case. For these purposes, there is no need to be defensive, not in the slightest. And I certainly try not to be. Am I ever wrong? Of course, on occasion, yes - I have had a doozie or two in my time, perhaps a number of them. But you try to feel secure about such lapses, knowing that we all err occasionally, and try as a whole to conform to an overall solid record of being as accurate and insightful as possible. While you get the occasional harsh attack, for the most part I have found that people will be charitable knowing that you may have spent no more than 10 or 15 minutes trying to address a sometimes complex topic. Better to give people the benefit of your insights if it is an area where you can do so than it is to leave something in the internet conversion that is wrong or off simply hanging out there. That is a great benefit of the internet. Back in the day, you had to dig deep to find out what people with expertise in their field were thinking and access to this was severely limited. The internet has changed all that. There may be a lot of slop out there but there are also many gems that are there for the taking. As writers, we should be ready to share, if not gems, at least our best thoughts on topics where people might find them helpful.
If I were to stray from my professional topics, then maybe I would be more defensive as well. But the author of this piece emphasizes how the internet may hinder academic writing and I see legal writing as at least broadly similar. So, my experience differs pretty markedly.
Just my two cents.