Vs死了 fuses 死了 straight onto the adjective as a fixed extreme (累死了); 得 opens a rated verdict behind a verb (累得不得了, 跑得很快). No 得 in Vs死了 — the extreme is built in.
V+Vs is action-verb plus a state that names its outcome (吃飽 = eat to full); Vs死了 is a state word plus 死了 to push that state to the extreme (餓死了 = hungry to death). The first word is the act in V+Vs, the state itself in Vs死了.
inserting 得: 我累得死了 → 我累死了
reading it as literal death: 我餓死了 → 餓 pushed to its extreme, 'starving'
stacking 很 with it: 很累死了 → 累死了 (死了 already maxes the scale)
English says 'dead tired', 'bored to death' — but puts dead/to-death as a loose phrase; learners reach for 得 or 很 to glue 死了 on instead of fusing it straight to the adjective.