Under-the-hood is an engine that is pretty modern though (at least for a vast majority of the websites I regularly use, and plenty are "Web 2.0"). It's not as updated in terms of web compatibility as Mozilla's Gecko, and I'm not going to hold my breath for that, even though I love this browser very much and have contributed code to the Pale Moon / UXP project. Trying to "catch up" in the WHATWG's "Living Standard" is just going to be an endless uphill battle because of Chrome doing implementations first before doing consultations with real stakeholders like website authors in writing the spec to see if the features they want to push to the rest of the web are really necessary and beneficial. It's amazing we're still able to make advancements on this front like getting Google's WebComponents supported or dynamic module imports.