It's not strictly necessary, but it is helpful in a lot of decks
In the article announcing the banning, Wizards suggested that it was willing to see if players would tolerate a "skill-testing, one-deck metagame." As such, it seems that a deck being 75% of the format doesn't automatically necessitate a banning
Monstrous Rage and Heartfire Hero, meanwhile, are key pieces of Standards Mono Red decks
If you must, make sure in pre-game chats that you ensure players are aware they should pack a deck with an alternate win-con or means to bypass them
Putrid Goblin Putrid Goblin is a dorky little zombie, but never underestimate persist
Bedrock Tortoise's ability doesn't actually change any creature's power