If a single account is maxed out, and when taking out that account utilization is in the single digits or low 10s, I fail to see why an algorithm couldn't figure out that this is for a lucrative offer (for example 0% for 12 months with 1% fee).
Because unsecured debt is unsecured debt. That 0% offer is great for you and you have every intention of paying it back responsibly. But things happen. Kids get cancer, family members die, cocaine habits are formed or reappear, people get hit by buses, recessions come, companies go BK.
Unsecured debt is a riskier investment for creditors.