Putin and most of the Russian military doctrine would beg to differ.
It depends on the nation and their political situation.
Since 1945, Russia hasn't shown that it can accept a war of mass casualties without political fallout. Russian military doctrine may say that it can, but Putin would be unwise to assume so.
Siege tanks are grouped with marines and firebats for protection, Marines and medics run with medics for assistance. Have your infantry out front. Move to a location, plant your troops, put your tanks in siege mode, rain hellfire down upon aerial defenses and approaching units so your Battlecruisers can come in with their Vulture and Wraith support to decimate a base.
It takes a village. You know, to destroy the other guys village. But still. Villages.
Do you now what's funny? Even RTS videogames like the Command and Conquer series or Star-Craft made this point clear early in our childhoods.
Tanks will be eaten alive by hoards of cheap disposable units, so you always had to support them with anti-infantry units if you wanted them to be useful in battle.