What if you open the same page in Firefox, Internet Explorer or any other desktop browser? The page loads and you only see a short message informing you that "you will need Google Chrome to install most apps, extensions and themes". That's the right thing to do and it's surprising that Google doesn't load a page because "your operating system is not supported just yet".
You can't install extensions if you use any other browser than Chrome (for desktop), but there are other reasons to open a web page. Maybe you want to read the reviews, write a review, check the screenshots. For now, you can install Chrome for Android or iOS and use the "request desktop site" feature to load the offending page.
Google Play does a much better job: it not only loads in almost any browser and operating system, but it also lets you install applications remotely.