There is certainly lots of information out there on this topic. Acrylic in and of itself isn’t particularly archival but artists’ acrylics are as archival as any other artist’s paint and maybe more-so. The pigments themselves are archival, some more so than others, and there are more of them. Acrylics use all the traditional pigments and newer, sometimes better ones. I think oil painters tend to be traditionalists and stick to traditional pigments. New pigments are just so ‘NEW’. My problem with oils is that the oil used is organic in nature. Usually Linseed, Poppy, Walnut and Safflower and there are probably others. So being organic they can be subject to degradation over time. The one thing that can be said about most of the old masters is that they were great experimenters. There are synthetic oils used in paint usually referred to as enamels but I haven’t seen their use in artist’s oil paint.
The one thing we don’t have is hundreds of years of history with acrylics. The manufacturers have done a great deal of testing that accelerates conditions the paint is exposed to over time. But this isn’t a replacement for actual time, so time will tell. Early acrylics definitely had some problems but they have been worked out over the last 60 years. Oils have had problems too but they were mostly due to how various artists mixed them and these problems were hundreds of years ago. With modern chemistry and techniques I opt for acrylics.
I paint because I enjoy it. I don’t paint for others or with much thought of money or a lasting legacy. Acrylic paints work well and have advantages so I like using them. If some people think they aren’t worth as much, I don’t care, it’s their money so they should buy art that they think is worth it. I’m not painting to eat; if I were I would starve.
I have heard from a few sources that acrylic paint uses less pigment than oil paint. This is silly since many manufacturers make both so why would they hold back on pigment with acrylic. Seems to me they could sell more, command more of the market, charge higher prices and make more money if they used the same or more pigment (most pigments are cheap). This doesn’t affect how long the paint lasts. There is nothing I’m aware of that limits the amount of pigment that is incorporated into acrylic paint. It’s like baking a cake. How much of any one ingredient can you put in?
Here are a couple of links that give more information: