<p>1) They're lazy</p><p>2) It sucks</p><p>3) Both</p><p>4) !?</p><p>5) It's secretly developed by Klingons and sharing the source would show proof of alien life to the entire world</p><p>6) You!</p><p><br></p><p>All of these are equally likely except one.</p>
<p>Not sure if i remember correctly but msft will not be completely retiring EdgeHTML. It will continue as an integral part of windows since it is a dependency for UWP. So, yeah, much like the rest of the system, EdgeHTML will remain closed source.</p>
<p>I assume because they're abandoning it and don't want fragmentation where people don't upgrade because there's no more EdgeHTML. I don't mind Edge too much but I know with work, I can't use it for most things because many companies don't have the programs working well with Edge. My company tests for Edge and makes sure it works accordingly, but having one less browser in the field saves us some development time…. </p>
<p>I assume it's risk vs reward.</p><p><br></p><p>Preparing code for open sourcing is not trivial, it takes time and effort, which means it has a cost.</p><p><br></p><p>The demand is low enough that they probably decided that the cost outweighs the benefits.</p><p><br></p>