In my opinion "crypto winter" is a stupid term coined to describe bear trends and to scare people away from being involved in the market. You have downtrends and uptrends. Or if there is constant sentiment over a period of time, bull markets and bear markets.
1) would've other crypto's survived during that time ?.
2) Why do Bitcoin survive during crypto winter and other crypto's finds it difficult to cope ?.
1) No, altcoins/tokens with no purpose have been killed by down trends because they either had no purpose or could not survive without crypto succeeding.
2) Bitcoin survives because it is a true cryptocurrency with strong, self-sustaining economics and a large population of members who are constantly aiming to improve it in several ways. Altcoins/tokens with similar foundations survive downtrends because they actually have some form of value. Altconis/tokens without one of these attributes fail once the hype has left the market.