I've been thinking about the liberalism beeline thing. I think I agree that it would be good to reduce the power of beelining towards liberalism, but I suspect it isn't the techpath that's the problem.
Here's my thinking on the matter, please correct me if you disagree:
I don't think the free beakers from liberalism is the really important thing there. On high difficulty levels the AI will typically be teching faster than the player, and the actual beaker cost of the free tech isn't really a big advantage. The advantage is that you get a head start on some particularly important techs. In particular, rifling, and the synergy between rifling and nationhood.
Here's a little anecdote from a recent game, it isn't very important, I've just written it to illustrate what I think the power of rifling is:
There are a few techs which grant a big step up in attack power, but it occurs to me that rifling is the only example in which there is no defensive tech that comes before it. For example, macemen struggle to beat crossbows, and crossbows come first. Archers come before axemen, and archers typically win if they are defending a city. Knights are a less well countered, because pikemen don't really come first, but longbows do come first. ... then there are riflemen. Riflemen beat everything that come before them. They are typcially fighting against knights, musketmen, and longbows and riflemen stomp them all. Even grenadiers struggle against riflemen when under attack. After riflemen the old pattern resumes. Machine guns beat infantry, fighter planes beat bombers, anti-tanks beat tanks, etc. So defence usually comes before offense except in the case of riflemen which are both the offensive and defence of their time. And this means that to get a strong military edge using riflemen, you only need to be 1 tech ahead of your enemies (only "Rifling") as opposed to most other cases where you need to get the offensive tech before they get the earlier defensive tech.
Meanwhile, at the same time as this anomaly, drafting becomes available. Suddenly instead of taking a few turns to build each unit you can get them instantly, and a flood of riflemen can appear from nowhere.
...
My point is that I think that the relationship between riflemen and the other units around that time might be a bit problematic, and that the problem is strongly amplified by drafting. I don't think liberalism is the problem. I think rifling is... but I don't really have any good ideas to improve it yet.
I do have some other thoughts on the matter, but I've already ranted enough for now... I'd better give you a chance to say "No. You've missed the point entirely. Rifling has very little to do with the liberalism beeline strategy."
[edit machine guns don't really come before infantry... they are about at the same time. But I think you can still see my point.]