On Kraken, you can buy quite a lot of major crypto directly with fiat.  So I don't think that this matters.  Moreover, if you buy "BTC" on an exchange, you are actually only buying an exchange IOU.  Nothing happens on the block chain, and no miner fees are paid for.  The fee is only paid when you "withdraw" your coins, that is, when you nicely demand your exchange, to send you real BTC or other when you try to redeem their promise (the IOU).  Until then, no real crypto coins are handled, all this is just on the web site of your exchange. 
So if you buy a BTC IOU, and you then exchange that BTC IOU for Zombie Coin IOU on the same exchange, I don't see how the high fees on the BTC block chain that has nothing to do with this, has anything to do with what you're doing.

Of course, if you want to buy BTC on exchange 1 and send it to exchange 2, you have to pay twice a block chain fee.  This is why it is a bad idea to use BTC for that.  Use something like LTC or BCH or another cheap fee coin, it is much cheaper.  The actual price of LTC doesn't matter.  The only thing that might matter is the volatility between you exchanging your BTC IOU into a LTC IOU, withdrawing them, receiving your LTC from exchange 1, and you depositing your LTC on exchange 2, and exchanging the LTC IOU into a BTC IOU.  LTC being a very fast chain, the price change (the volatility risk) should be small.   You are only exposed for about 10 minutes or so to LTC volatility.  Whether LTC trades at $1 or at $1000, doesn't matter at all.  The amount of BTC you had on exchange 1 will be close to the amount of BTC on exchange 2 ; if the two trade fees on the exchange are small compared to the BTC block fee, you win on fees, it is faster and smoother.