I have had a 1 sat/vbyte transaction that has been stuck in the mempool for quite a while. Even with current low fees, it's been stuck for weeks.
I had to wait a few hours before I could do the replace-by-fee (RBF) because Bitcoin Core I used for that transaction wasn't synced yet with the blockchain and I had no funds left to increase the fee at that moment. I couldn't do Child Pays For Parent (CPFP) as I do not have access to the private key of the receiving address.
So, naively, I started looking into Bitcoin accelerators (mempool.space, viaBTC, Antpool, F2Pool, etc). All were charging fees ranging between 30,000 to 60,000k sats. viaBTC has a limited number of free acceleration per hour, but with my 1sat/vByte, I did not qualify. Some also asked for an email address to first make an account with them.
I also used https://bitaccelerate.com/ to rebroadcast my transaction to all the nodes, but as the fee was too low, it didn't make a difference. As recommended in #262460
I thus decided against the accelerators, waited patiently for a few hours, and managed to use RBF for less than 1500 sats. And it's really not that difficult. E.g. in Bitcoin Core, it's a few clicks using the GUI.
So my question to get back to my title ("unless you really have to"): Is there any reason to use accelerators over RBF/CPFP other than (arguably) the tools' user-friendliness?