I think Lion's Heart is well underrated in the guides. While I don't think it is worth pumping endlessly into, there is a certain mechanic I have found that I think is very important to new players.
If you get 100 soul points when you have none, the increase in your damage is astronomical compared to getting 100 points when you already have 1k or more, so for beginners there is a problem, do I spend my points to ultimately make my character stronger while taking a temporary debuff? or do I wait until it is not so much of a hit?
Here comes Lion's Heart to save the day! While getting it will increase the cost of other artifacts, and there are other damage sources that are better, Lion's heart gives a guilt free way to improve your character and spend on incidentals. How you may ask?
Once you have Lion's heart, always spend 2 points leveling Lion's heart to every point you spend elsewhere.
Now you may be asking, "Why would I spend triple the points?" The reason is it allows the player to buy higher tier sciences without taking a dps hit. It allows you to recycle the artifacts until you get the artifact that will help you the most, without taking a dps hit. You are able to get the Hero Souls Totem from the store to boost your soul gain without taking a dps hit.
This technique provides a smoother experience for the new player, while also allowing them to benefit from events, and things they may not be aware of yet.