And still no transactional DDL in MySQL
Very few database systems support online DDL, which unlike a transaction, does not require undo or rollback resources. Of course one must have a rollback procedure if something fails, but you need one for transactions too, just in case.
An online rollback is far lest costly than a transactional rollback, because and online rollback is just undoing what you did. Added a column you didn't want in one query? Remove it again in another, very quickly.
TokuDB (a mysql/mariadb storage engine) supported all DDL as an online operation. But percona killed it in favour of TokuMX, the MongoDB equivalent.
TokuMX has no upgrade path to wired tiger, only one major customer at Percona (I can't say who it is) and no engineers.
Any kind of DDL is tricky and requires users to RTFM for the intricacies of their chosen database. One size rarely fits all.
I really wish Percona would reconsider their decision to deprecate it.
After Percona took over TokuDB's creator TokuTek, they wasted so much of their development time and money on TokuMX (Percona's fractal tree-enabled MongoDB server) only to abandon it in 2017.
That money would have been better spent on TokuDB development to allow it to match the features present in InnoDB like generated columns, spatial indexing, fulltext Indexes and Galera.
TokuDB still has many users and MyRocks is just no substitute.