Bookings made by internet reservation channels like Expedia and Travelocity are growing at up to 20% per quarter. The sheer volume of bookings that these websites make gives them the ability to to obtain higher commissions, reduced room rates, or other significant concessions from Starwood - this means significantly lowered profit margin for HOT.
Additionally, these websites make brand names obsolete. Starwood relies heavily on its brand names to attract customers but internet reservation channels book hotels based on lowest available price. This means that Starwood will have trouble distinguishing itself from its cheaper competitors and lose customers to them.