It's true, here is a Painblade capture of a disabled, then boarded, then cleared by melee weapon only, Prophesy II.
Of course I am in an unlikely armor set and using a Painblade that by my past experience is highly unlikely to acquire over the course of a long time and many kills, watching day after day for these pieces to drop. The gear does a lot of mitigation and the weapon a lot of damage. Without the mitigation you need to be careful and pick your fights carefully. Without the big damage number you need to do hits and fight longer more than I would do, so I would not use melee unless geared like this as it would be too much effort for what reason, just shoot them and move on unless you have a good damage number and mitigation so as to move quickly.
I really think that making your gear and weapon like I have with this character should be enabled at the crafting stations and not require console commands to acquire. Doing so makes the players experience much more fun IMO.