My main problem with LBD, as implemented in Valheim, is that it is so uninteresting and devoid of joy -- impersonal, really. It just happens. You do something, and then automatically you get better at that very thing. The outcome is that I don't care about my skills and how good I am at certain things when playing Valheim, because I can't influence it anyway so it doesn't matter. I rarely look at my skills, I rarely think about them. Basically, Valheim is not made more interesting or enjoyable because of how they have implemented skills and character development.
With the system now in 7D2D, I get a little kick whenever I get a new skill point because I looooove using that skill point to get better at what I want to be better at. To some extent, nights are for looking at the perk tree and planning what I will do with the next few skill points I get. I derive a lot of pleasure from this. Right now I use a stun baton in my MP game and there are at least three perks that I can spend skills point in to get better at swinging that thing. What should I pick? What goes with the rest of my character build? And the rest of the players? Or should I spend them somewhere else entirely? I get a lot of enjoyment from this. It is part of why 7D2D is such a great game, for me.
I get that it isn't as realistic as LBD. But it is not totally unrealistic, either. What I do most of in a game is typically where I would spend the skill points anyway, thus emulating LBD. And if I suddenly decide to get better at something I haven't really done much, say, shoot a rifle, then I picture I can do that because I have read some magazines about rifles or some of my fellow players have helped me learn it. I can rationalize it fairly easily without it breaking immersion. To me, the thing with any of these systems (LBD or magazines or perks) which breaks immersion or makes it all unrealistic, is the fact that we develop our characters so quickly, especially physical characteristics. That is totally unrealistic, much more so than the ability to get better at something you haven't done excessively.
To be constructive, a hybrid system where physical stats are increased at least partly though LBD and more theoretical skills are learnt through reading, might work and be even better - I am just not sure it is worth the effort of implementing. I feel there are many other things that are more important.