are those instructions for climbing to cruising altitude where the airplane is going so slow it gives you a warning to not go below 140? might be a different instruction if the airplane is going full speed.
semp
Flaps need to be retracted in increments. Stall speeds are lower with flaps down, so if you retract them too quickly before establishing a positive rate of climb, you will go down instead of up. It can be very dangerous as this all takes place low to the ground, obviously. I'm sure a lot of CFIs can tell you stories of doing go-arounds, and having students instinctively retract flaps before adding power and/or establishing a positive rate of climb.
So I would agree with you, semp.