You evidently don't know what you are talking about.
The turbo button as one other poster stated was used clean back to the 8088 days and continued to be on some systems throught the 8086, the 286, the 486 and even on the 586.
Some systems even had three speedsteps. Turbo mode was the higher speed.
You are correct that some early software which had did not have any timing restrictions written into the programming had a hard time running at faster speeds, these were mostly early games which were written around a 6 mhz clock speed. For these you would run the system at the lower stock speeds rather than in turbo mode.