Tanks provide more than sufficient firepower, with armoured protection to allow them to destroy most strong points with direct fire. However, they are effectively "blind" when closed down, when in urban environments, which allows the enemy to approach closely and attack them, unless they have sufficient infantry supporting them. Indeed, the idea of attacking urban sites with armoured forces alone is considered crazy by most tacticians. People seem to forget that today, most armies utilise "combined arms teams" - armour, infantry and other supporting arms to provide them with sufficient firepower and the means to overcome obstacles/strong points when they encounter them.
This was confirmed by the Israelis in 1982 when the invaded Lebanon. They tried to send M113s with infantry inside to support tanks in the cities they were attacking. The infantry were reluctant to leave their APCs and as a result everybody suffered casualties from RPGs and ATGWs. Nowadays, the Israelis kick their mounts out and make them walk when they reach the outer limits of the cities.