What's left of Flash on legacy websites should die. HTML5 is preferred, and will run on Android and (I assume) iOS tablets and phones. Except for programming a codeplug, I don't use my 10 yr old Windows 7 Asus netbook; there is no need as my Samsung Galaxy Tab S3 LTE does everything I need. I can understand Radioreference's difficulties in migrating from Flash as the site is huge, but sooner or later it will come to pass...
My own website is simple and small, but the best thing I did 5 or 8 years ago was dump the convoluted Dreamweaver code and redo the pages in HTML5/CSS3. No muss with browser compatibility. To work on the pages I use QuickEdit Pro and FtpCafe on my tablet and phone from anywhere I have a cell or WiFi signal. Giddyup.