I've incorporated PC backstory into my two current campaigns. To me it's really important to make the stakes of the adventure as personal as possible. I'll be even more aggressive in using backstory in future campaigns.
It takes practice to get players (and DMs) to make actionable backstories. I think to use backstory properly you need to do two things.
First, backstories need to be concise and evocative. Ideally that means 3 to 5 single-sentence bullet points. Players don't need to write a short story about their mercenary legion's betrayal on the battlefield; "lone survivor of a betrayed mercenary company" is enough. 13th Age's backgrounds and One Unique Things are great examples of this.
Second, assuming you're not co-authoring the campaign with players ala 13th Age or Blades In The Dark, you need to give players strong prompts to tie into your storyline. Don't be afraid to use leading questions. For example, if I was playing Descent Into Avernus, I might ask players to build their backstories off of questions like: "For what are you willing to sell your soul? Name a person, place, or thing in Elturel that you would kill (or die) for. Is your relationship with the authority figures in Elturel positive, negative, or in some way conflicted?"
As a default, I may ask players to write a single sentence each on an interesting and exciting aspect related to their class, race, and background. That should result in three sentences which, hopefully, have great story hooks. Example: "I'm a warrior, like my father before me, and his father before him. The shaman of my clan told me I was destined to betray someone I loved. I was kicked out of the brewer's guild after refusing to pay off a Zhentarim protection racket."
It takes practice to get players (and DMs) to make actionable backstories. I think to use backstory properly you need to do two things.
First, backstories need to be concise and evocative. Ideally that means 3 to 5 single-sentence bullet points. Players don't need to write a short story about their mercenary legion's betrayal on the battlefield; "lone survivor of a betrayed mercenary company" is enough. 13th Age's backgrounds and One Unique Things are great examples of this.
Second, assuming you're not co-authoring the campaign with players ala 13th Age or Blades In The Dark, you need to give players strong prompts to tie into your storyline. Don't be afraid to use leading questions. For example, if I was playing Descent Into Avernus, I might ask players to build their backstories off of questions like: "For what are you willing to sell your soul? Name a person, place, or thing in Elturel that you would kill (or die) for. Is your relationship with the authority figures in Elturel positive, negative, or in some way conflicted?"
As a default, I may ask players to write a single sentence each on an interesting and exciting aspect related to their class, race, and background. That should result in three sentences which, hopefully, have great story hooks. Example: "I'm a warrior, like my father before me, and his father before him. The shaman of my clan told me I was destined to betray someone I loved. I was kicked out of the brewer's guild after refusing to pay off a Zhentarim protection racket."