I agree that lack of weapons for direct assault limits some of the upside benefits as in "you cannot directly win a war on defensive moves" but you can force a better, safer, more advantageous outcome. In effect, Russia is losing a war of attrition on it's economy and materiel side. It does have massive manpower and stocks. It doesn't have infinite supply of economic resilience and home front tolerance for a failing economy undermines Kremlin myths.
Sometimes, not losing is the best you can get pending more help.
Ukraine is not losing.
Russia is not winning.