The plugins sit in a local directory. Very easy to modify.
You still have no control over obsidian itself. Any change can and will break plugins. So you either settle with one version for the next decade, or you have to maintain them. This is just the normal dependency-hell that every project has, where you have to compromise with external dependency and their whims. Just that neither plugins nor obsidian (to some degree) are the level of professional software-projects in that regard.
And let's not talk about changing Obsidian on fundamental levels. You have even less control on how it works on everything which is not accessible by plugins.
I could see the dataview plugin as an example (even though I don't use that one personally) but most other plugins seem like they just add more convenient ways to do something that would be still pretty simple to do manually. (Templates for example).
Depends on what you are doing. But the whole task & project-management-corner is constantly moving. Everything which modified the editor and preview was also regular breaking in the last years. For example, there were some plugins adding banners at the top of documents, or background-images or some icons. Or plugins modifying the yaml-area. They were all breaking multiple times when Obsidian was switching to the new live-preview-editor, then on changing frontmatter to properties, and on some other occasion IIRC. Usually after some months a new plugin appears, or someone forks the old one and fixes it. But as a user, it's pretty annoying to constantly have something breaking outside your control and getting stripped of features you want/need for various reasons.
Obsidian is useful, but far from being stable long-term yet. It's still very young.
> I could see the dataview plugin as an example
Yes, dataview was also very unstable the first 2 years or so, switching code and concepts, breaking old code along the line. It seems to be stable now, as the focus is on datacore.
> but most other plugins seem like they just add more convenient ways to do something that would be still pretty simple to do manually. (Templates for example).
Does it matter what a plugin is doing? If it breaks, it's a loss, whether it's crucial or just annoying.
To me, the "dialects" of Markdown have never made any difference in using it, even between applications. I think the only non-standard (for whatever "standard" means in Markdown) markup I use in Obsidian is "%%" to indicate comments. That's certainly something easy enough to search for should it be necessary in a text editor.
Not really.. This problem runs far deeper than most are willing to see. First, Obsidian is using a personalized flavour of markdown, and seconds, for many heavy features it's leaning strongly on plugins which are prone to break or even die. Obsidian has a vibrant plugin-community, which also seems to die really fast. This becomes even more critical by plugins dying from changes in Obsidian itself. So while Obsidian is in theory a nice open app, it's longevity-aspect is really awful. I already had many features and plugins dying in the last years, and who know how much more will break in the next 20 years. Simply switching to another text-editor will not do, because they won't offer the missing features. So at best, you are just not losing your data, but you still won't have the tooling to use them.
Someone creating their own system, where they have full control over everything, even if they will have to sacrifice some benefit in the short run, just makes sense in a bigger picture.