Srila Prabhupada:They are not fit for sannyasa

Srimad Bhagavatam
Canto 8, Chapter 2, TEXT 30
Translation
Thereafter, because of being pulled into the water and fighting for many long years, the elephant became diminished in his mental, physical and sensual strength. The crocodile, on the contrary, being an animal of the water, increased in enthusiasm, physical strength and sensual power.
Purport
In the fighting between the elephant and the crocodile, the difference was that although the elephant was extremely powerful, he was in a foreign place, in the water. During one thousand years of fighting, he could not get any food, and under the circumstances his bodily strength diminished, and because his bodily strength diminished, his mind also became weak and his senses less powerful. The crocodile, however, being an animal of the water, had no difficulties. He was getting food and was therefore getting mental strength and sensual encouragement. Thus while the elephant became reduced in strength, the crocodile became more and more powerful. Now, from this we may take the lesson that in our fight with maya we should not be in a position in which our strength, enthusiasm and senses will be unable to fight vigorously. Our Krsna consciousness movement has actually declared war against the illusory energy, in which all the living entities are rotting in a false understanding of civilization. The soldiers in this Krsna consciousness movement must always possess physical strength, enthusiasm and sensual power. To keep themselves fit, they must therefore place themselves in a normal condition of life. What constitutes a normal condition will not be the same for everyone, and therefore there are divisions of varnasrama—brahmana, ksatriya, vaisya, sudra, brahmacarya, grhastha, vanaprastha and sannyasa. Especially in this age, Kali-yuga, it is advised that no one take sannyasa.
asvamedham gavalambham
sannyasam pala-paitrkam
devarena sutotpattim
kalau pañca vivarjayet
[Cc. Adi 17.164]
(Brahma-vaivarta Purana)
From this we can understand that in this age the sannyasa-asrama is forbidden because people are not strong. Sri Caitanya Mahaprabhu showed us an example in taking sannyasa at the age of twenty-four years, but even Sarvabhauma Bhattacarya advised Sri Caitanya Mahaprabhu to be extremely careful because He had taken sannyasa at an early age. For preaching we give young boys sannyasa, but actually it is being experienced that they are not fit for sannyasa. There is no harm, however, if one thinks that he is unfit for sannyasa; if he is very much agitated sexually, he should go to the asrama where sex is allowed, namely the grhastha-asrama. That one has been found to be very weak in one place does not mean that he should stop fighting the crocodile of maya. One should take shelter of the lotus feet of Krsna, as we shall see Gajendra do, and at the same time one can be a grhastha if he is satisfied with sexual indulgence. There is no need to give up the fight. Sri Caitanya Mahaprabhu therefore recommended, sthane sthitah sruti-gatam tanu-van-manobhih. One may stay in whichever asrama is suitable for him; it is not essential that one take sannyasa. If one is sexually agitated, he can enter the grhastha-asrama. But one must continue fighting. For one who is not in a transcendental position, to take sannyasa artificially is not a very great credit. If sannyasa is not suitable, one may enter the grhastha-asrama and fight maya with great strength. But one should not give up the fighting and go away.”

(January 7, 1977 Bombay)
“If you want woman you get yourself married, live respectfully. We have no objection. But this hypocrisy should be stopped. There have been so many fallen down. First of all there will be no sannyasi anymore. I have got very bad experience. And at least, we are not going to create new sannyasis. And those who have fallen down, let them marry, live like respectable gentlemen. I have no objection.