Why do climbers complain that at high altitudes they cannot make hot and strong tea?

1) Boiling is the process of vaporization throughout the volume of water. Water boils when the pressure inside the bubbles of water vapor becomes greater than the atmospheric pressure outside. Then the bubbles grow and are pushed up by the force of Archimedes.
2) At high altitudes, atmospheric pressure is lower than on the surface of the earth. The lower the external pressure, the lower the vapor pressure for boiling water should be, the lower the boiling point of water.
3) Since the water passes into steam, without warming up to 100 degrees, the flavoring substances of tea are poorly dissolved in it.