100% in general, famously the leman russ tank has a comically small amount of armor. But when it comes to space marines specifically, imo part of the point is that the symbol of the Imperium's strength is spread too thin and is completely lacking, which is part of why the Imperium has been in a constant spiraling decline for over ten thousand years. I'll admit this take makes a bit less sense since they started advancing the timeline.
100% in general, famously the leman russ tank has a comically small amount of armor. But when it comes to space marines specifically, imo part of the point is that the symbol of the Imperium's strength is spread too thin and is completely lacking, which is part of why the Imperium has been in a constant spiraling decline for over ten thousand years. I'll admit this take makes a bit less sense since they started advancing the timeline.