Leveling DoL classes alone is perfectly viable.

Being able to craft isn't particularly necessary for DoL. Especially since you can still just make Gil by selling things you gather and simply purchase crafted gear to be able to harvest the highest tier items.

In addition, solo crafting jobs are also viable. Sure, you won't be able to as easily make all the highest tier items, but they should still be doable, especially if you make enough Gil to just purchase the crafted gear.

This should become even easier too, since Dev's have mentioned they wanted to take the focus off of needing to use cross-class skills on crafting jobs. Which likely could be done in ShB.